feat(voice): DAVE E2E receive-side decrypt — unblocks Pas 12

Vendored fork: discord-ext-voice_recv 0.5.3a+echo.dave1

Patches the receive pipeline to handle Discord's mandatory DAVE E2E
encryption on voice gateway v=8. Without this, opus_decode raised
"corrupted stream" on every received packet in a DAVE-active room and
voice-to-voice never connected.

DAVE patch (vendor/discord-ext-voice-recv/reader.py):
- `_maybe_dave_decrypt(rtp_packet)`: gate mirrors discord.py 2.7.1
  `voice_state.can_encrypt`. Uses davey's `can_passthrough(user_id)` to
  branch — peers in passthrough send transport-only packets that pass
  through verbatim; peers in DAVE epoch go through `davey.decrypt`.
- Hooked in `callback()` between transport decrypt and feed_rtp;
  drops on decrypt failure without killing the reader thread.
- Bumps __version__ to '0.5.3a+echo.dave1' (PEP 440 local segment) so a
  contract test can fail fast on accidental upstream-sync overwrite.

Pipeline fixes uncovered while testing DAVE end-to-end:
- src/voice/pipeline.py: silero-vad v6+ requires exactly 512 samples per
  call at 16kHz; our 100ms window (1600 samples) was silently raising
  ValueError → VAD always returned False → STT never fired. Slice the
  window into 512-sample chunks. Bump whisper beam_size 1→5 and add a
  Romanian `initial_prompt` — transcriptions go from "Eco salt." gibberish
  to "Echo, salutare, te rog spune-mi cât este ora."
- src/voice/tts_stream.py: EchoStreamingAudioSource.read() returns a 20ms
  silence frame instead of b'' on empty queue. Empty return is treated
  by Discord as end-of-stream and kills the player, so any TTS pushed
  later would be silently discarded.
- src/adapters/discord_voice.py: actually attach EchoStreamingAudioSource
  to the voice client after the wakeup beep (chained via `after=`),
  which was missing entirely — TTS frames had no consumer.

Tests:
- tests/test_voice_recv_dave.py: 11 unit + callback integration tests
  covering bypass paths, can_passthrough gate, decrypt error handling.
- tests/test_voice_adapter_contract.py: +test_voice_recv_fork_version
  and +test_voice_connection_state_has_dave_attrs guards against
  upstream drift on either side.

Config:
- config.json: voice.allowed_user_ids whitelist for Marius's user id.

Status: voice-to-voice loop closes end-to-end (DAVE → VAD → Whisper →
Claude → Supertonic → audio out). Latency is ~8-13s per turn, which is
out of scope for this commit — see TODOS.md for the real-time UX
follow-up plan.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

config.json

@@ -104,6 +104,12 @@
   "ollama": {
     "url": "http://10.0.20.161:11434"
   },
+  "voice": {
+    "allowed_user_ids": ["949388626146517022"],
+    "user_name": "Marius",
+    "default_voice": "M2",
+    "auto_leave_minutes": 5
+  },
   "paths": {
     "personality": "personality/",
     "tools": "tools/",