Complete rewrite inspired by Morse Expert / CW Skimmer (VE3NEA):
- CwFFT: radix-2 FFT (256-point) for time-frequency analysis
- CwSpectrogram: sliding-window waterfall (40 cols x 33 bins, 8ms resolution)
- CwBayesianDecoder: Gaussian probability replaces hard dit/dash thresholds
- CwChannelTracker: multi-channel peak detection (up to 3 signals)
- CwDecoder: integrates all components, monitors 200-1200 Hz simultaneously
Key advantages over v2 (ggmorse):
- Frequency-agnostic: full spectrum monitored, not locked to one tone
- Multi-channel: tracks multiple signals in parallel
- Bayesian: probability-based decisions, not hard ratios
- Doppler tolerant: frequency drift just moves energy between bins
- After initial pitch lock, re-scan every ~8 seconds in a narrow
±100 Hz window around the current pitch estimate
- Only re-lock if pitch change > 20 Hz (avoids jitter)
- Helps maintain lock when Doppler tracking has residual error
- 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
- Add DopplerFrequencyCalculator utility with passband mapping + Doppler correction
- Add MHz input UI with real-time 1Hz refresh during pass
- Add kHz offset for downlink frequency correction
- TX/RX fields on same row for compact layout
- 40 unit tests covering linear/FM/inverted transponders
atsunatsu