Implements the errand detail panel with three context-aware views:
- Active: live agent output via AgentOutputViewer, chat input, Mark Done/Abandon
- Pending review/conflict: diff block, conflict notice with file list, Merge/Delete/Abandon
- Merged/abandoned: read-only diff, info line with relative date, Delete only
Follows TaskSlideOver.tsx patterns: Framer Motion slide-in, backdrop, Escape key close.
Shift+click skips window.confirm on all destructive actions.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
