Add forced action handling, turn boundary detection, and DB persistence:
- Check for pending forced actions before allowing regular actions
- Only specified player can act during forced action (except resign)
- Only specified action type allowed during forced action
- Detect turn boundaries (turn number OR current player change)
- Persist to Postgres at turn boundaries for durability
- Include pending_forced_action in GameActionResult for client
New exceptions: ForcedActionRequiredError
Tests: 11 new tests covering forced actions, turn boundaries, and
pending action reporting. Total 47 tests for GameService.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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