Added
- Comprehensive test suite with 991 passing tests
- Unit tests for serializers, models, cache, and configuration
- Integration tests for storage backends, services, and API
- Test framework dependencies (JUnit 5, MockK, MockBukkit, kotlinx-coroutines-test)
- SQLite JDBC driver for test environment
- Testing documentation section in README

Fixed
- Fixed null pointer exception in `InventoryService` when using null group for global bypass
- Changed internal set implementation to support null values for global bypass tracking
- Fixed `WorldPattern` equality comparison
- Two patterns with the same regex string now correctly compare as equal
- Added proper `equals()` and `hashCode()` implementations