- Created state cleanup system (stateCleanup.ts) with:
* Size limit cleanup: Limit number of items in arrays/normalized state
* Age limit cleanup: Remove items older than specified time
* Custom cleanup: User-defined cleanup functions
* Support for arrays, normalized state, and nested objects
- Added cleanupMiddleware for automatic periodic cleanup
- Added performCleanup function for manual cleanup
- Comprehensive test suite (9 tests, all passing)
- Prevents memory leaks by cleaning unused state data
