- Add Worker class with CPU/GPU support
- Add WorkerPool for orchestrating multiple workers
- Support dynamic add/remove workers at runtime
- Add health monitoring with graceful shutdown
- Add backend/config.py with Pydantic settings validation
- Support for standalone, provider, and hybrid operation modes
- Multi-database backend configuration (SQLite/PostgreSQL/MariaDB)
- Environment variable validation with helpful error messages
- Worker and Whisper model configuration
