- Replace default=datetime.utcnow with server_default=func.now() across all 16 models (17 columns) for consistent, timezone-aware timestamps from PostgreSQL
- Upgrade DateTime columns to DateTime(timezone=True) for timestamptz storage
- Configure SQLAlchemy engine pool: pool_size=20, max_overflow=10, pool_recycle=3600, pool_pre_ping=True
- Remove unused datetime imports from model files
