- Create BlockedTriageModal component at src/components/shared/blocked-triage-modal.tsx
- Implements modal with blocked task triage functionality
- Uses deriveBlockedIds and buildBlockedByTree from kanban lib
- Each row shows blocker chain and has inline archetype picker
- Modal is scrollable and closes via Escape/close button
- Add corresponding tests at tests/components/blocked-triage-modal.test.tsx
- Register test in package.json test script
