- Implement tests for HandlerDispatcher in `tests_v4/test_handler_dispatcher.py`, covering initialization, invocation, cancellation, argument building, result consumption, error handling, and handler execution.
- Introduce tests for Plugin loading functionalities in `tests_v4/test_loader.py`, including plugin specification, discovery, environment management, and loading components and handlers.
- Added internal capability for handler invocation in SupervisorRuntime.
- Implemented lifecycle hooks (on_start, on_stop) in Star class and PluginWorkerRuntime.
- Updated CapabilityRouter to support request_id in call and stream handlers.
- Refactored message handling in PeerRuntime to include request_id.
- Introduced tests for API contract, legacy adapter, and migration scenarios.
- Improved WebSocketServerTransport to manage connection state more effectively.
- Enhanced plugin loading and discovery to maintain compatibility with legacy systems.