- Reduce .env.example to only DATABASE_URL
- Simplify backend/config.py to only read database connection
- All other settings now managed via database and Web UI
- 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
