feat: MCP server + audio effects chain
MCP Server:
- Full Model Context Protocol server (backend/mcp_server.py)
- 5 tools: generate_speech, list_voices, list_personalities,
list_languages, check_health
- 2 resources: voice://{id}, history://recent
- stdio + SSE transports for Claude Desktop / Cursor / remote agents
- Example config: mcp.json
Audio Effects Chain:
- 6 presets: Broadcast, Cinematic, Podcast, Warm, Bright, Raw
- Configurable pipeline via apply_effects_chain() with pedalboard
- Effects: highpass, lowpass, compressor, reverb, noise_gate, eq, limiter
- GET /tools/effects API for frontend preset picker
- Graceful fallback when pedalboard isn't installed