- Add EdgeTTSAdapter to bin/deepdive_tts.py (provider key: "edge-tts")
default voice: en-US-GuyNeural, no API key required
- Add EdgeTTS class to intelligence/deepdive/tts_engine.py
- Update HybridTTS to try edge-tts as fallback between piper and elevenlabs
- Add --voice-memo flag to bin/night_watch.py for spoken nightly reports
- Add edge-tts>=6.1.9 to requirements.txt
- Create docs/voice-output.md documenting all providers and fallback chain
- Add tests/test_edge_tts.py with 17 unit tests (all mocked, no network)
Fixes#1126
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
