Implements "Option A: Single Source of Truth" from type audit recommendations.
**Phase 1: Consolidate GameValidator**
- Remove redundant GameValidator re-declaration from SDK types
- SDK now properly re-exports GameValidator from validation types
- Eliminates confusion about which validator interface to use
**Phase 2: Eliminate Move Type Duplication**
- Remove duplicate game-specific move interfaces from validation/types.ts
- Add re-exports of game move types from their source modules
- Maintains single source of truth (game types) while providing convenient access
**Changes:**
- `src/lib/arcade/game-sdk/types.ts`: Import & re-export GameValidator instead of re-declaring
- `src/lib/arcade/validation/types.ts`: Replace duplicate move interfaces with re-exports
- `__tests__/room-realtime-updates.e2e.test.ts`: Fix socket-server import path
**Impact:**
- Zero new type errors introduced
- All existing functionality preserved
- Clear ownership: game types are source of truth
- Improved maintainability: changes in one place
**Verification:**
- TypeScript compilation: ✅ No new errors
- Server build: ✅ Successful
- All pre-existing errors unchanged (AbacusReact module resolution, etc.)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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