Add smart self-healing for sync errors

Implements automatic repair mechanism for pending changes with sync errors:
- Projects: validates and fixes empty name/code fields
- Configurations: ensures project references exist or assigns system project
- Clears errors and resets attempts to give changes another sync chance

Backend:
- LocalDB.RepairPendingChanges() with smart validation logic
- POST /api/sync/repair endpoint
- Detailed repair results with remaining errors

Frontend:
- Auto-repair section in sync modal shown when errors exist
- "ИСПРАВИТЬ" button with clear explanation of actions
- Real-time feedback with result messages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/qfs/main.go

@@ -1653,6 +1653,7 @@ func setupRouter(cfg *config.Config, local *localdb.LocalDB, connMgr *db.Connect
 			syncAPI.POST("/push", syncHandler.PushPendingChanges)
 			syncAPI.GET("/pending/count", syncHandler.GetPendingCount)
 			syncAPI.GET("/pending", syncHandler.GetPendingChanges)
+			syncAPI.POST("/repair", syncHandler.RepairPendingChanges)
 		}
 	}