Add README, faster-whisper backend, and session fixes

- README explaining experimental/transparency purpose
- faster-whisper STT backend (fw-stt.mjs, faster-whisper-server.py, install-faster-whisper.sh)
- Bug fixes: Buffer alignment in on_audio, --debug-waveform URL parsing, silent fetch errors, instant dispatch timer leak
- Global uncaughtException/unhandledRejection handlers in query-demo.mjs
- Design docs: CHANGELOG, COMMAND-DISPATCH, INTERFACE-THEORY, VOICE-POLICY
- Systemd service unit templates

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -1,11 +1,6 @@
 node_modules/
 models/
 venv/
-*.ogg
-*.wav
-*.mp3
-*.onnx
-*.bin
 package-lock.json
 __pycache__/
-*.pyc
+build/