Talk Spotter 2.1.0-rc1 (experimental)

Release candidate built from the experimental-refactor branch. Not merged to main yet.

Highlights

• RTL-SDR DSP rebuilt (lib/dsp.py): polyphase decimation (~2x less CPU at 960 kS/s — matters on Raspberry Pi), proper instant-attack/slow-release AGC for SSB/AM replacing per-chunk peak normalization, fixed deviation-referenced scaling for FM, anti-alias filtering on the AM/FM paths, stateful DC blocking, and a comfort-noise dither that measurably improves Vosk recognition.
• Validated end-to-end against Vosk (real speech, modulated and demodulated, strong and weak signals): recognition ≥ 2.0.2 in all six scenarios; weak AM 5% → 79%, weak FM 88% → 94% F1.
• Thread-safety fixes: command parser locking (no more double-post risk), network posting moved off the audio thread, sources join worker threads before closing devices (fixes potential crash on exit).
• Dead code removed, POTA/SOTA posting deduplicated, 60+ new tests, new tools/validate_demod_e2e.py regression gate.

The .deb below is built by CI from this tag.