Checks the full voice environment and reports what's missing:
- Python packages: discord.py, PyNaCl, davey, STT/TTS providers
- System tools: Opus codec (macOS + Linux paths), ffmpeg
- Environment: bot token, allowed users (resolved to usernames), API keys
- Configuration: STT/TTS provider, voice mode state
- Bot permissions: live Discord API check for Connect, Speak, VAD, etc.
All sensitive values are masked. Gracefully handles missing deps,
invalid tokens, API timeouts, and unreachable Discord API.
