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>
7fec60b26d