- Add test_engine.py with 100% coverage for engine.py
- Tests for Engine class initialization
- Tests for choose_move with various scenarios
- Tests for best move parsing and validation
- Tests for checkmate and stalemate detection
- Add test_lichess_api.py with 98% coverage for lichess_api.py
- Tests for API initialization and request handling
- Tests for stream_events with proper infinite loop handling
- Tests for challenge accept/decline
- Tests for game streaming and move submission
- Tests for rate limit handling and retry logic
- Remove unreachable return statement in lichess_api.make_move
Coverage: engine.py 17% -> 100%, lichess_api.py 0% -> 98%
