Issue #4 from code review - multi-step database operations were not
wrapped in transactions, risking partial state on failure.
Changes:
- Modified save_play() and update_game_state() in DatabaseOperations
to accept optional session parameter for transaction grouping
- Wrapped resolve_play() DB operations in single atomic transaction
- Wrapped resolve_manual_play() DB operations in single atomic transaction
- Transaction commits atomically or rolls back entirely on failure
Pattern: When session provided, use flush() for IDs without committing;
caller controls transaction. When no session, create internal transaction.
All 739 unit tests passing.
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Co-Authored-By: Claude <noreply@anthropic.com>
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