- Add task-changes-file-list--compact CSS modifier class with tighter padding, gaps, and stat margins
- Apply compact modifier to TaskChangesTab file list container
- Add regression tests verifying compact class is present on TaskChangesTab and absent on CommitDiffTab
- Document compact spacing treatment in dashboard README
- Create CommitDiffTab component with commit list and inline diff display
- Integrate Commits tab into TaskDetailModal with conditional visibility
- Add comprehensive tests for CommitDiffTab rendering, selection, and diff display
- Add TaskDetailModal tests for tab visibility based on task PR info
- Remove stale changeset and unused store test code
