feat(cw): add built-in CW Morse code decoder for linear transponders

- Add CwDsp with FIR bandpass filter, envelope detection, Goertzel tone detector
- Add CwDecoder with real-time Morse timing analysis and character lookup
- Add CW state/actions to RadarState, wire into RadarViewModel
- Add collapsible CW decoder panel to transceivers page
- 19 unit tests covering DSP, Morse table, and decoder state
- Shares IAudioCapture with SSTV, auto-stops SSTV when CW starts

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarScreen.kt

@@ -171,12 +171,13 @@ private fun PagerCard(
             ) { pageIndex ->
                 when (pages[pageIndex]) {
                     RadarPage.Transceivers -> TransceiversPage(
-                        transceivers = uiState.transceivers.transmitters,
-                        selectedUuid = uiState.transceivers.selectedUuid,
-                        orbitalPos = uiState.orbitalPos,
-                        radioControl = uiState.radioControl,
-                        onAction = onAction
-                    )
+                                    transceivers = uiState.transceivers.transmitters,
+                                    selectedUuid = uiState.transceivers.selectedUuid,
+                                    orbitalPos = uiState.orbitalPos,
+                                    cw = uiState.cw,
+                                    radioControl = uiState.radioControl,
+                                    onAction = onAction
+                                )
                     RadarPage.Sstv -> SstvPage(
                         sstv = uiState.sstv,
                         dopplerFrequency = uiState.transceivers.selectedFrequency?.let { formatFrequency(it) },

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarState.kt

@@ -62,7 +62,8 @@ data class RadarState(
     val moonPosition: CelestialComputer.MoonPosition? = null,
     val transceivers: TransceiverSubState = TransceiverSubState(),
     val radioControl: RadioControlSubState = RadioControlSubState(),
-    val sstv: SstvSubState = SstvSubState()
+    val sstv: SstvSubState = SstvSubState(),
+    val cw: CwSubState = CwSubState()
 )
 
 enum class SstvStatus { Idle, Recording }
@@ -77,6 +78,19 @@ data class SstvSubState(
     val diagnosticsMetrics: SstvQualityMetrics? = null
 )
 
+// --- CW Decoder ---
+
+enum class CwStatus { Idle, Listening }
+
+data class CwSubState(
+    val status: CwStatus = CwStatus.Idle,
+    val hasPermission: Boolean = false,
+    val decodedText: String = "",
+    val cwToneFreq: Float = 700f,
+    val isExpanded: Boolean = false,
+    val signalStrength: Float = 0f
+)
+
 sealed interface RadarAction {
     data class AddToCalendar(val name: String, val aosTime: Long, val losTime: Long) : RadarAction
     data class SelectTransmitter(val uuid: String) : RadarAction
@@ -96,4 +110,12 @@ sealed interface RadarAction {
     data object SstvReset : RadarAction
     data class SstvSelectMode(val modeName: String) : RadarAction
     data class SstvPermissionResult(val granted: Boolean) : RadarAction
+
+    // CW actions
+    data object CwStartListening : RadarAction
+    data object CwStopListening : RadarAction
+    data object CwReset : RadarAction
+    data class CwSetToneFreq(val freq: Float) : RadarAction
+    data class CwToggleExpanded(val expanded: Boolean) : RadarAction
+    data class CwPermissionResult(val granted: Boolean) : RadarAction
 }

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/RadarViewModel.kt

@@ -34,6 +34,7 @@ import com.rtbishop.look4sat.core.domain.repository.ISensorsRepo
 import com.rtbishop.look4sat.core.domain.repository.ISettingsRepo
 import com.rtbishop.look4sat.core.domain.sstv.LineRecoveryStrategy
 import com.rtbishop.look4sat.core.domain.sstv.SstvDecoder
+import com.rtbishop.look4sat.core.domain.cw.CwDecoder
 import com.rtbishop.look4sat.core.domain.usecase.IAudioCapture
 import com.rtbishop.look4sat.core.domain.usecase.IAddToCalendar
 import com.rtbishop.look4sat.core.domain.usecase.ISaveImage
@@ -70,6 +71,8 @@ class RadarViewModel(
     private var transponders: List<SatRadio> = emptyList()
     private var sstvDecoder: SstvDecoder? = null
     private var sstvRecordingJob: Job? = null
+    private var cwDecoder: CwDecoder? = null
+    private var cwListeningJob: Job? = null
 
     // Celestial positions change slowly, recompute at most once per minute
     private var lastCelestialUpdateMs = 0L
@@ -272,6 +275,25 @@ class RadarViewModel(
                 sstvDecoder?.clearPixels()
                 _uiState.update { it.copy(sstv = it.sstv.copy(currentFrame = null)) }
             }
+
+            // CW actions
+            is RadarAction.CwPermissionResult -> {
+                _uiState.update { it.copy(cw = it.cw.copy(hasPermission = action.granted)) }
+                if (action.granted) initCwDecoder()
+            }
+            RadarAction.CwStartListening -> startCwListening()
+            RadarAction.CwStopListening -> stopCwListening()
+            RadarAction.CwReset -> {
+                cwDecoder?.resetDecoder()
+                _uiState.update { it.copy(cw = it.cw.copy(decodedText = "")) }
+            }
+            is RadarAction.CwSetToneFreq -> {
+                _uiState.update { it.copy(cw = it.cw.copy(cwToneFreq = action.freq)) }
+                cwDecoder = CwDecoder(sampleRate = audioCapture.sampleRate, cwToneFreq = action.freq)
+            }
+            is RadarAction.CwToggleExpanded -> {
+                _uiState.update { it.copy(cw = it.cw.copy(isExpanded = action.expanded)) }
+            }
         }
     }
 
@@ -392,6 +414,48 @@ class RadarViewModel(
         _uiState.update { it.copy(sstv = it.sstv.copy(status = SstvStatus.Idle)) }
     }
 
+    private fun initCwDecoder() {
+        if (cwDecoder == null) {
+            cwDecoder = CwDecoder(
+                sampleRate = audioCapture.sampleRate,
+                cwToneFreq = _uiState.value.cw.cwToneFreq
+            )
+        }
+    }
+
+    private fun startCwListening() {
+        if (cwListeningJob?.isActive == true) return
+        // Stop SSTV if running (audio capture is shared)
+        stopSstvRecording()
+        initCwDecoder()
+        cwDecoder?.resetDecoder()
+        _uiState.update { it.copy(cw = it.cw.copy(status = CwStatus.Listening)) }
+        cwListeningJob = viewModelScope.launch {
+            // Collect decoded text flow
+            launch {
+                cwDecoder?.decodedTextFlow?.collect { text ->
+                    _uiState.update { it.copy(cw = it.cw.copy(decodedText = text)) }
+                }
+            }
+            // Collect signal strength
+            launch {
+                cwDecoder?.signalStrength?.collect { strength ->
+                    _uiState.update { it.copy(cw = it.cw.copy(signalStrength = strength)) }
+                }
+            }
+            // Capture audio and feed to decoder
+            audioCapture.audioFlow().collect { buffer ->
+                cwDecoder?.processBuffer(buffer)
+            }
+        }
+    }
+
+    private fun stopCwListening() {
+        cwListeningJob?.cancel()
+        cwListeningJob = null
+        _uiState.update { it.copy(cw = it.cw.copy(status = CwStatus.Idle)) }
+    }
+
     companion object {
         // SSTV Decoder Tuning Parameters
         // ==============================

feature/radar/src/main/java/com/rtbishop/look4sat/feature/radar/TransceiversPage.kt

@@ -40,10 +40,13 @@ import androidx.compose.foundation.lazy.itemsIndexed
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material3.Button
+import androidx.compose.material3.ElevatedCard
 import androidx.compose.material3.FilterChip
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
@@ -80,6 +83,7 @@ fun TransceiversPage(
     transceivers: List<SatRadio>,
     selectedUuid: String?,
     orbitalPos: OrbitalPos?,
+    cw: CwSubState,
     radioControl: RadioControlSubState,
     onAction: (RadarAction) -> Unit,
     modifier: Modifier = Modifier
@@ -105,6 +109,7 @@ fun TransceiversPage(
                     radio = radio,
                     isExpanded = isExpanded,
                     orbitalPos = orbitalPos,
+                    cw = cw,
                     radioControl = radioControl,
                     onAction = onAction,
                     onToggle = { onAction(RadarAction.SelectTransmitter(radio.uuid)) }
@@ -142,6 +147,7 @@ private fun TransceiverItem(
     radio: SatRadio,
     isExpanded: Boolean,
     orbitalPos: OrbitalPos?,
+    cw: CwSubState,
     radioControl: RadioControlSubState,
     onAction: (RadarAction) -> Unit,
     onToggle: () -> Unit
@@ -237,6 +243,7 @@ private fun TransceiverItem(
             ExpandedRadioControl(
                 radio = radio,
                 orbitalPos = orbitalPos,
+                cw = cw,
                 radioControl = radioControl,
                 onAction = onAction
             )
@@ -308,6 +315,7 @@ private fun UnifiedFrequencyRow(
 private fun ExpandedRadioControl(
     radio: SatRadio,
     orbitalPos: OrbitalPos?,
+    cw: CwSubState,
     radioControl: RadioControlSubState,
     onAction: (RadarAction) -> Unit
 ) {
@@ -425,6 +433,15 @@ private fun ExpandedRadioControl(
             modifier = Modifier.fillMaxWidth()
         )
 
+        // CW decoder panel (linear transponders only)
+        if (DopplerFrequencyCalculator.isLinearTransponder(radio)) {
+            CwDecoderPanel(
+                cw = cw,
+                onAction = onAction,
+                modifier = Modifier.fillMaxWidth()
+            )
+        }
+
         // Control buttons
         Row(horizontalArrangement = Arrangement.spacedBy(4.dp)) {
             if (!radioControl.txPanel.isConnected && !radioControl.rxPanel.isConnected) {
@@ -602,6 +619,113 @@ private fun DopplerFrequencyCalculator(
 
 private enum class EditedField { TX, RX }
 
+@Composable
+private fun CwDecoderPanel(
+    cw: CwSubState,
+    onAction: (RadarAction) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Column(
+        modifier = modifier,
+        verticalArrangement = Arrangement.spacedBy(4.dp)
+    ) {
+        // Header row: expand/collapse toggle
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .clickable { onAction(RadarAction.CwToggleExpanded(!cw.isExpanded)) },
+            horizontalArrangement = Arrangement.SpaceBetween,
+            verticalAlignment = Alignment.CenterVertically
+        ) {
+            Text(
+                text = stringResource(R.string.radar_cw_decoder),
+                fontSize = 14.sp,
+                fontWeight = FontWeight.Medium,
+                color = MaterialTheme.colorScheme.primary
+            )
+            Icon(
+                painter = painterResource(id = R.drawable.ic_arrow),
+                contentDescription = null,
+                tint = MaterialTheme.colorScheme.onSurfaceVariant,
+                modifier = Modifier
+                    .size(20.dp)
+                    .rotate(if (cw.isExpanded) 270f else 90f)
+            )
+        }
+
+        AnimatedVisibility(visible = cw.isExpanded) {
+            Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
+                // Control buttons row
+                Row(
+                    horizontalArrangement = Arrangement.spacedBy(8.dp),
+                    modifier = Modifier.fillMaxWidth()
+                ) {
+                    if (cw.status == CwStatus.Idle) {
+                        Button(
+                            onClick = { onAction(RadarAction.CwStartListening) },
+                            modifier = Modifier.weight(1f)
+                        ) {
+                            Text(stringResource(R.string.radar_cw_start))
+                        }
+                    } else {
+                        Button(
+                            onClick = { onAction(RadarAction.CwStopListening) },
+                            modifier = Modifier.weight(1f)
+                        ) {
+                            Text(stringResource(R.string.radar_cw_stop))
+                        }
+                    }
+                    OutlinedButton(
+                        onClick = { onAction(RadarAction.CwReset) },
+                        modifier = Modifier.weight(1f)
+                    ) {
+                        Text(stringResource(R.string.radar_cw_reset))
+                    }
+                }
+
+                // Signal strength indicator
+                if (cw.status == CwStatus.Listening && cw.signalStrength > 0f) {
+                    val strengthPct = (cw.signalStrength * 100).toInt()
+                    Text(
+                        text = "Signal: $strengthPct%",
+                        fontSize = 12.sp,
+                        color = if (cw.signalStrength > 0.5f) Color(0xFF4CAF50)
+                        else if (cw.signalStrength > 0.2f) Color(0xFFFFC107)
+                        else MaterialTheme.colorScheme.onSurfaceVariant
+                    )
+                }
+
+                // Decoded text output
+                ElevatedCard(
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .height(120.dp)
+                ) {
+                    Column(
+                        modifier = Modifier
+                            .fillMaxSize()
+                            .padding(8.dp)
+                    ) {
+                        Text(
+                            text = "Decoded:",
+                            fontSize = 12.sp,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant
+                        )
+                        Spacer(modifier = Modifier.height(4.dp))
+                        Text(
+                            text = cw.decodedText.ifEmpty { "Waiting for CW signal..." },
+                            fontSize = 16.sp,
+                            fontWeight = FontWeight.Medium,
+                            color = MaterialTheme.colorScheme.onSurface
+                        )
+                    }
+                }
+            }
+        }
+    }
+}
+
 @Composable
 private fun FrequencyText(frequency: Long?, modifier: Modifier = Modifier) {
     val text = frequency?.let {