Lodgify MCP Server

# Add unit tests for get_occupancy_summary The PR #33 introduces error handling for invalid date strings in `get_occupancy_summary`, but there are no tests covering these cases. ## Tasks - [ ] Write pytest tests verifying that invalid `start_date` or `end_date` return `{"success": False}` with the expected error message. - [ ] Test that invalid date entries in calendar data also trigger the error path.