feat: media player API, web player panel, and Hope music MCP

- web/media_server.py: FastAPI service owning the permanent library
  (library.json + ./media volume), yt-dlp YouTube Music search, queued
  download jobs with mp3 transcode (ffmpeg), per-room player desired
  state, and an HTTPS proxy for external live-stream URLs.
- agent/media_mcp.py: Hope tools — search_music, play_song,
  offer_song_choices, pause/resume/stop/skip/seek, now_playing,
  list_library, add_stream.
- agent/agent.py: media toolset wiring + conversation rule (music
  playing disables the agent mic; re-engaging pauses music).
- web UI: slide-out Music panel (search, suggestions, library, live
  stream add, play/pause, ±10s, seek, volume) with a reconciling poller
  and media_state data-channel reports.
- token server returns the minted room name; nginx serves /media/files
  as static (native Range) and proxies /media/api to the media server.
- supervisord runs media-server; compose mounts ./media and adds
  ffmpeg to the image.

agent/pyproject.toml

@@ -9,10 +9,14 @@ description = "Real-time voice assistant: Azure STT/TTS + Gemma LLM via LiveKit
 requires-python = ">=3.10,<3.15"
 
 dependencies = [
+    "fastapi>=0.141.1",
+    "httpx>=0.28.1",
     "livekit-agents[mcp]~=1.7",
     "livekit-plugins-azure~=1.7",
     "livekit-plugins-openai~=1.7",
     "python-dotenv",
+    "uvicorn>=0.52.4",
+    "yt-dlp>=2026.8.19",
 ]
 
 [tool.setuptools.packages.find]