Replace blocking rtl_stdout.read() with select()+os.read() so the
decoder thread emits diagnostic heartbeat scope events when rtl_fm
produces no PCM data (common in direct sampling mode). Add waiting-state
rendering in the scope canvas and hide the generic placeholder/status
bar for morse mode.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add automatic gain control (AGC) before Goertzel processing to normalize
quiet audio from direct sampling mode where the -g gain flag has no effect.
Fix broken adaptive threshold bootstrap by adding a 50-block warm-up phase
that collects magnitude statistics before seeding noise floor and signal peak.
Lower threshold ratio from 50% to 30% for better weak-CW sensitivity.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
New signal mode for decoding Morse code (CW) transmissions via SDR.
Includes route blueprint, utility decoder, frontend UI, and tests.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
