Add unit tests for hasValuableMoves and integration with game-over

[SorraTheOrc]

Summary

Add comprehensive tests for the new hasValuableMoves() function and verify its integration with the game-over detection flow.

Tests to Add

Unit tests for hasValuableMoves (in BeleagueredCastleRules.test.ts)

1. Board with only non-valuable moves detects as game-over: Construct a state where the only legal moves are tableau-to-tableau shuffles that don't expose new cards. Verify hasValuableMoves() returns false.

2. Board with at least one valuable move is NOT game-over: Construct a state where at least one move exposes a new card or creates a new foundation opportunity. Verify hasValuableMoves() returns true.

3. Foundation move is always valuable: A state where the only legal move is a tableau-to-foundation move. Should return true.

4. Empty tableau columns: Edge case where some columns are empty but moves between remaining columns don't help.

5. Single-card columns: State with single-card columns where moves expose the empty column (which is a new move target).

6. No legal moves at all: Verify returns false (consistent with hasNoMoves).

7. Fresh deal has valuable moves: A normal deal should always have at least one valuable move.

8. State is not mutated: Verify the state is identical before and after calling hasValuableMoves.

Integration tests (in Integration.test.ts)

9. Full game detects stuck state: Play a game that reaches a stuck position and verify the game ends appropriately.

Acceptance Criteria

• All listed test cases are implemented and pass
• All existing tests continue to pass
• Tests cover the key edge cases from the parent work item's AC

[SorraTheOrc]

\n\n**worklog**\n\nClosed with reason: Added 10 unit tests for hasValuableMoves covering all acceptance criteria. Merged in abd7ad4.