feat(FEAT-006): add validation and loop state API endpoints

Implemented:
- POST /api/missions/features/:featureId/validate - triggers validation run
- GET /api/missions/features/:featureId/validation-loop - returns loop snapshot
- GET /api/missions/features/:featureId/validation-runs - returns run history with pagination
- GET /api/missions/validation-runs/:runId - returns run detail with assertion results
- POST /api/missions/recover - triggers recovery of active missions
- SSE events for milestone:validation:updated via assertion CRUD and link/unlink

All 4xx/5xx responses use consistent {"error": "message"} format.
Uses existing badRequest, notFound, internalError helpers.

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

packages/cli/src/commands/dashboard.ts

@@ -791,6 +791,7 @@ export async function runDashboard(port: number, opts: { paused?: boolean; dev?:
     modelRegistry,
     automationStore,
     missionAutopilot,
+    missionExecutionLoop,
     heartbeatMonitor,
     pluginStore,
     pluginLoader,