- Adds "Radar" nav item to AppLayout between Agents and Inbox
- Creates /radar route with validateSearch for timeRange/status/initiativeId/mode filters
- Summary stat cards for questions, messages, subagents, compactions aggregates
- Agent activity table with client-side sorting on all 10 columns (default: started desc)
- Real-time SSE updates via useLiveUpdates invalidating agent namespace
- Loading skeleton (5 rows) and empty state messaging
- Non-zero metric cells show cursor-pointer for future drilldown dialogs
- 12-test suite covering rendering, sorting, filtering, nav, and states
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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