[AG-01] agent.py — AgentSession v1.3 with prewarm, Silero VAD, Deepgram STT, Cartesia TTS

## AG-01: agent.py — AgentSession v1.3 with prewarm, Silero VAD, Deepgram STT, Cartesia TTS Section: LiveKit Agent | Milestone: M2 | Owner: Desktop Lu ### Failing Tests - **agent_file** (file_exists): File `c8-audio/agent/agent.py` must exist - **pyproject** (file_exists): File `c8-audio/agent/pyproject.toml` must exist - **env_example** (file_exists): File `c8-audio/agent/.env.example` must exist - **agent_session** (grep): Pattern `AgentSession` in `c8-audio/agent/agent.py` (need 1+ matches) - **prewarm_fn** (grep): Pattern `def prewarm` in `c8-audio/agent/agent.py` (need 1+ matches) - **silero_vad** (grep): Pattern `silero\.VAD\.load` in `c8-audio/agent/agent.py` (need 1+ matches) - **deepgram_stt** (grep): Pattern `deepgram\.STT` in `c8-audio/agent/agent.py` (need 1+ matches) - **cartesia_tts** (grep): Pattern `cartesia\.TTS` in `c8-audio/agent/agent.py` (need 1+ matches) - **preemptive_gen** (grep): Pattern `preemptive_generation` in `c8-audio/agent/agent.py` (need 1+ matches) - **false_interrupt** (grep): Pattern `resume_false_interruption` in `c8-audio/agent/agent.py` (need 1+ matches) - **transcription_out** (grep): Pattern `transcription_enabled` in `c8-audio/agent/agent.py` (need 1+ matches) - **metrics_collector** (grep): Pattern `UsageCollector|metrics` in `c8-audio/agent/agent.py` (need 1+ matches) - **room_name_parse** (grep): Pattern `c8-voice|room\.name` in `c8-audio/agent/agent.py` (need 1+ matches) ### Acceptance Criteria - File `c8-audio/agent/agent.py` must exist - File `c8-audio/agent/pyproject.toml` must exist - File `c8-audio/agent/.env.example` must exist - File matching `c8-audio/agent/agent.py` must contain pattern `AgentSession` - File matching `c8-audio/agent/agent.py` must contain pattern `def prewarm` - File matching `c8-audio/agent/agent.py` must contain pattern `silero\.VAD\.load` - File matching `c8-audio/agent/agent.py` must contain pattern `deepgram\.STT` - File matching `c8-audio/agent/agent.py` must contain pattern `cartesia\.TTS` - File matching `c8-audio/agent/agent.py` must contain pattern `preemptive_generation` - File matching `c8-audio/agent/agent.py` must contain pattern `resume_false_interruption` - File matching `c8-audio/agent/agent.py` must contain pattern `transcription_enabled` - File matching `c8-audio/agent/agent.py` must contain pattern `UsageCollector|metrics` - File matching `c8-audio/agent/agent.py` must contain pattern `c8-voice|room\.name` ### Codebase Conventions - Trilingual comments: // EN: ... // VI: ... // ES: ... - SPEC section refs in comments - Zod at module level with .safeParse() - (supabase as any) with eslint-disable - NextResponse.json() responses - Error format: { error: 'message' }