feat(models): chatterbox-turbo and chatterbox-mtl adapters

feat(api,models): FastAPI app with /api/health, /api/models, activate, /api/generate + chatterbox-en adapter

feat(registry): active-model swap with async lock and SSE event bus

feat(models): ModelAdapter protocol + is_valid_adapter check

feat(zerogpu): decorate() shim for HF ZeroGPU compatibility

feat(schemas): pydantic models for ParamSpec/ModelInfo/Health/Errors

feat(audio): wav validation, write helper, mono/16k normalization

feat(device): auto-detect cuda/mps/cpu with env override

chore: scaffold python project (requirements, gitignore, pytest, package skeleton)