feat(voice): Pas 2 — install voice deps, vendor discord-ext-voice-recv, setup assets

Foundation pentru Discord voice-to-voice pipeline.

- requirements.txt: faster-whisper, silero-vad, num2words, numpy, PyNaCl
- vendor/discord-ext-voice-recv/: vendored la commit ac04ea7b09 (bump version
  0.5.3a) — Discord voice protocol fragil, upstream hobby fork. Adapter layer
  in src/voice/_discord_voice_adapter.py izolează churn (swap la py-cord =
  doar acel fișier rescris). VENDOR_INFO.md documentează update procedure.
- tools/voice_setup.py: idempotent setup script — libopus check, ffmpeg
  check, Supertonic reachable, faster-whisper/silero-vad warm, assets
  generation. Exit 0 = green, 1 = needs human (currently libopus missing
  needs `sudo apt install -y libopus0`).
- assets/voice/: thinking.wav (filler "Stai puțin să-mi adun gândurile",
  ~2.8s), mhm.wav (listener noise), beep_200ms.wav (wake-up tone 880Hz).
- src/voice/__init__.py: package stub.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

vendor/discord-ext-voice-recv/pyproject.toml

@@ -0,0 +1,27 @@
+[build-system]
+requires = ["setuptools", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[tool.black]
+line-length = 125
+skip-string-normalization = true
+
+[tool.isort]
+profile = "black"
+combine_as_imports = true
+combine_star = true
+line_length = 125
+
+[tool.pyright]
+include = [
+    "discord/ext/voice_recv",
+]
+exclude = [
+    "**/__pycache__",
+    "build",
+    "dist",
+]
+reportUnnecessaryTypeIgnoreComment = "warning"
+# reportUnusedImport = "error"
+pythonVersion = "3.8"
+typeCheckingMode = "basic"