feat(maf): Phase 5 - action coordinator, approval flow, frontend MAF roundtable pages
- Backend: action_coordinator, capability_snapshot, event_normalizer, tool_executor updates
- Backend: approved_tool_executor with write guard, action leases, migration script
- Frontend: maf-roundtable module (API client, event timeline, approval cards, fact flow panel)
- Frontend: MafRoutes, MafSessionsPage, MafRunDetailPage
- Tests: action_leases, migration_phase5, phase5_entry_e2e, real_write_e2e/http_e2e
- Docs: update implementation plan
Co-authored-by: Cursor <cursoragent@cursor.com>
