Close gui2_feature_parity track after implementing all features
and conducting manual and automated verification.
Key Achievements:
- Integrated event-driven architecture and MCP client.
- Ported API hooks and performance diagnostics.
- Implemented Prior Session Viewer.
- Refactored UI to a Hub-based layout.
- Added agent capability toggles.
- Achieved full theme integration.
- Developed comprehensive test suite.
Note: Remaining UI display issues for text panels in the comms and
tool call history will be addressed in a subsequent track.
