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

core/presentation/src/main/res/values/strings.xml

@@ -86,6 +86,11 @@
     <string name="radar_doppler_offset_hint">Offset (kHz)</string>
     <string name="radar_doppler_info">For linear transponders, type one frequency to see the other</string>
 
+    <string name="radar_cw_decoder">CW Decoder</string>
+    <string name="radar_cw_start">Start</string>
+    <string name="radar_cw_stop">Stop</string>
+    <string name="radar_cw_reset">Clear</string>
+
     <!-- Map screen -->
     <string name="map_prev">Prev</string>
     <string name="map_next">Next</string>