feat: keep mutual state across nav + overlay station-B track on main radar

- MutualViewModel is Activity-scoped, so returning from Radar keeps query results
- TrackSampleData gains time field for live cut-off
- Removed standalone mutual card from radar page
- RadarViewCompose draws optional dashed station-B track + current dot
- RadarScreen builds trackB from mutual data up to current time

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

@@ -32,10 +32,8 @@ import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.pager.HorizontalPager
 import androidx.compose.foundation.pager.rememberPagerState
@@ -73,10 +71,8 @@ import com.rtbishop.look4sat.core.presentation.formatFrequency
 import com.rtbishop.look4sat.core.presentation.getDefaultPass
 import com.rtbishop.look4sat.core.presentation.isVerticalLayout
 import com.rtbishop.look4sat.core.presentation.layoutPadding
-import com.rtbishop.look4sat.feature.mutual.ElevationCurveChart
-import com.rtbishop.look4sat.feature.mutual.MutualRadarView
-import com.rtbishop.look4sat.feature.mutual.TrackSample
 import kotlinx.coroutines.launch
+import kotlin.math.PI
 
 private enum class RadarPage(val title: String) {
     Transceivers("Transceivers"),
@@ -121,6 +117,17 @@ private fun RadarScreen(
     val addToCalendar: () -> Unit = {
         uiState.currentPass?.let { onAction(RadarAction.AddToCalendar(it.name, it.aosTime, it.losTime)) }
     }
+    // Live station-B track overlay: samples up to "now" (recomposed each second tick)
+    val timeNow = System.currentTimeMillis()
+    val trackB = mutualData.trackSamples
+        .filter { it.time <= timeNow }
+        .map {
+            OrbitalPos(
+                azimuth = it.azimuthB * PI / 180.0,
+                elevation = it.elevationB * PI / 180.0,
+                time = it.time
+            )
+        }
     Column(
         modifier = Modifier
             .layoutPadding()
@@ -144,17 +151,11 @@ private fun RadarScreen(
             }
         }
         if (isVertical) {
-            RadarCard(uiState, Modifier.weight(1f))
-            if (mutualData.samples.isNotEmpty()) {
-                MutualElevationCard(mutualData, Modifier.weight(1f))
-            }
+            RadarCard(uiState, trackB, Modifier.weight(1f))
             PagerCard(uiState, onAction, requestMicPermission, Modifier.weight(1f))
         } else {
             Row(horizontalArrangement = Arrangement.spacedBy(6.dp)) {
-                RadarCard(uiState, Modifier.weight(1f))
-                if (mutualData.samples.isNotEmpty()) {
-                    MutualElevationCard(mutualData, Modifier.weight(1f))
-                }
+                RadarCard(uiState, trackB, Modifier.weight(1f))
                 PagerCard(uiState, onAction, requestMicPermission, Modifier.weight(1f))
             }
         }
@@ -210,7 +211,11 @@ private fun PagerCard(
 }
 
 @Composable
-private fun RadarCard(uiState: RadarState, modifier: Modifier = Modifier) {
+private fun RadarCard(
+    uiState: RadarState,
+    trackB: List<OrbitalPos> = emptyList(),
+    modifier: Modifier = Modifier
+) {
     val satellitePos = uiState.orbitalPos
     val shouldAnimateBorder = satellitePos?.aboveHorizon == true && satellitePos.eclipsed
     // Always call these composables unconditionally — conditional composable calls violate
@@ -243,6 +248,7 @@ private fun RadarCard(uiState: RadarState, modifier: Modifier = Modifier) {
                 RadarViewCompose(
                     item = position,
                     items = uiState.satTrack,
+                    trackB = trackB.takeIf { it.isNotEmpty() },
                     azimElev = uiState.orientationValues,
                     shouldShowSweep = uiState.shouldShowSweep,
                     shouldUseCompass = uiState.shouldUseCompass,
@@ -318,35 +324,3 @@ private fun RadarLabel(
         }
     }
 }
-
-@Composable
-private fun MutualElevationCard(mutualData: MutualPassData, modifier: Modifier = Modifier) {
-    ElevatedCard(modifier = modifier) {
-        Column(modifier = Modifier.fillMaxSize().padding(8.dp)) {
-            if (mutualData.trackSamples.isNotEmpty()) {
-                MutualRadarView(
-                    trackSamples = mutualData.trackSamples.map {
-                        TrackSample(
-                            time = 0L,
-                            azimuthA = it.azimuthA,
-                            elevationA = it.elevationA,
-                            azimuthB = it.azimuthB,
-                            elevationB = it.elevationB
-                        )
-                    },
-                    labelA = mutualData.labelA,
-                    labelB = mutualData.labelB
-                )
-                Spacer(Modifier.height(4.dp))
-            }
-            if (mutualData.samples.isNotEmpty()) {
-                ElevationCurveChart(
-                    samples = mutualData.samples,
-                    startTime = mutualData.startTime,
-                    endTime = mutualData.endTime,
-                    maxElev = mutualData.maxElev
-                )
-            }
-        }
-    }
-}

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

@@ -71,6 +71,8 @@ private const val SWEEP_DURATION_MS = 8_000
 fun RadarViewCompose(
     item: OrbitalPos,
     items: List<OrbitalPos>,
+    trackB: List<OrbitalPos>? = null,
+    trackBColor: Color = MaterialTheme.colorScheme.tertiary,
     azimElev: Pair<Float, Float>,
     shouldShowSweep: Boolean,
     shouldUseCompass: Boolean,
@@ -107,18 +109,23 @@ fun RadarViewCompose(
     var cachedSweepColor by remember { mutableStateOf(Color.Unspecified) }
     var trackPath by remember { mutableStateOf(Path()) }
     var trackEffect by remember { mutableStateOf(PathEffect.cornerPathEffect(0f)) }
+    // Station-B overlay track (dashed)
+    var cachedTrackBRef by remember { mutableStateOf<List<OrbitalPos>?>(null) }
+    var trackBPath by remember { mutableStateOf(Path()) }
     // ShaderBrush is cached to avoid allocating a new GPU shader object every frame
     var cachedSweepBrush by remember { mutableStateOf<ShaderBrush?>(null) }
 
     Canvas(modifier = modifier.aspectRatio(1f)) {
         val radius = size.minDimension / 2f * 0.95f
         // Rebuild track path and sweep brush when canvas size or track data changes
-        if (radius != cachedRadius || items !== cachedItemsRef) {
+        if (radius != cachedRadius || items !== cachedItemsRef || trackB !== cachedTrackBRef) {
             trackPath = createTrackPath(items, radius)
             trackEffect = createTrackEffect(trackPath)
+            trackBPath = trackB?.let { createTrackPath(it, radius) } ?: Path()
             cachedSweepBrush = makeSweepBrush(center, primaryColor)
             cachedRadius = radius
             cachedItemsRef = items
+            cachedTrackBRef = trackB
             cachedSweepColor = primaryColor
         } else if (primaryColor != cachedSweepColor) {
             // Rebuild brush on theme change without waiting for a size change
@@ -131,6 +138,19 @@ fun RadarViewCompose(
             drawElevationLabels(radius, primaryColor, measurer)
             translate(center.x, center.y) {
                 drawTrack(trackPath, trackEffect, aimColor, primaryColor)
+                // Station-B overlay: dashed track + current position dot
+                if (trackB != null && trackB.isNotEmpty() && !trackBPath.isEmpty) {
+                    drawPath(
+                        trackBPath, trackBColor,
+                        style = Stroke(STROKE_WIDTH, pathEffect = PathEffect.dashPathEffect(floatArrayOf(18f, 12f)))
+                    )
+                    val lastB = trackB.last()
+                    if (lastB.elevation > 0) {
+                        val posB = sph2Cart(lastB.azimuth, lastB.elevation, radius.toDouble())
+                        drawCircle(trackBColor, 26f, posB, style = Stroke(2f))
+                        drawCircle(trackBColor, 12f, posB)
+                    }
+                }
                 if (item.elevation > 0) {
                     drawPosition(item, radius, animScale, primaryColor)
                 }