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>

internal/handlers/sync.go

@@ -419,6 +419,26 @@ func (h *SyncHandler) GetPendingChanges(c *gin.Context) {
 	})
 }
 
+// RepairPendingChanges attempts to repair errored pending changes
+// POST /api/sync/repair
+func (h *SyncHandler) RepairPendingChanges(c *gin.Context) {
+	repaired, remainingErrors, err := h.localDB.RepairPendingChanges()
+	if err != nil {
+		slog.Error("repair pending changes failed", "error", err)
+		c.JSON(http.StatusInternalServerError, gin.H{
+			"success": false,
+			"error":   err.Error(),
+		})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"success":          true,
+		"repaired":         repaired,
+		"remaining_errors": remainingErrors,
+	})
+}
+
 // SyncInfoResponse represents sync information for the modal
 type SyncInfoResponse struct {
 	// Connection

internal/localdb/localdb.go

@@ -1041,6 +1041,129 @@ func (l *LocalDB) GetPendingCount() int64 {
 	return l.CountPendingChanges()
 }
 
+// RepairPendingChanges attempts to fix errored pending changes by validating and correcting data.
+// Returns the number of changes repaired and a list of errors that couldn't be fixed.
+func (l *LocalDB) RepairPendingChanges() (int, []string, error) {
+	var erroredChanges []PendingChange
+	if err := l.db.Where("last_error != ?", "").Find(&erroredChanges).Error; err != nil {
+		return 0, nil, fmt.Errorf("fetching errored changes: %w", err)
+	}
+
+	if len(erroredChanges) == 0 {
+		return 0, nil, nil
+	}
+
+	repaired := 0
+	var remainingErrors []string
+
+	for _, change := range erroredChanges {
+		var repairErr error
+		switch change.EntityType {
+		case "project":
+			repairErr = l.repairProjectChange(&change)
+		case "configuration":
+			repairErr = l.repairConfigurationChange(&change)
+		default:
+			repairErr = fmt.Errorf("unknown entity type: %s", change.EntityType)
+		}
+
+		if repairErr != nil {
+			remainingErrors = append(remainingErrors, fmt.Sprintf("%s %s %s: %v",
+				change.Operation, change.EntityType, change.EntityUUID[:8], repairErr))
+			continue
+		}
+
+		// Clear error and reset attempts
+		if err := l.db.Model(&PendingChange{}).Where("id = ?", change.ID).Updates(map[string]interface{}{
+			"last_error": "",
+			"attempts":   0,
+		}).Error; err != nil {
+			remainingErrors = append(remainingErrors, fmt.Sprintf("clearing error for %s: %v", change.EntityUUID[:8], err))
+			continue
+		}
+
+		repaired++
+	}
+
+	return repaired, remainingErrors, nil
+}
+
+// repairProjectChange validates and fixes project data
+func (l *LocalDB) repairProjectChange(change *PendingChange) error {
+	project, err := l.GetProjectByUUID(change.EntityUUID)
+	if err != nil {
+		return fmt.Errorf("project not found locally: %w", err)
+	}
+
+	modified := false
+
+	// Fix Code: must be non-empty
+	if strings.TrimSpace(project.Code) == "" {
+		if project.Name != nil && strings.TrimSpace(*project.Name) != "" {
+			project.Code = strings.TrimSpace(*project.Name)
+		} else {
+			project.Code = project.UUID[:8]
+		}
+		modified = true
+	}
+
+	// Fix Name: use Code if empty
+	if project.Name == nil || strings.TrimSpace(*project.Name) == "" {
+		name := project.Code
+		project.Name = &name
+		modified = true
+	}
+
+	// Fix OwnerUsername: must be non-empty
+	if strings.TrimSpace(project.OwnerUsername) == "" {
+		project.OwnerUsername = l.GetDBUser()
+		if project.OwnerUsername == "" {
+			return fmt.Errorf("cannot determine owner username")
+		}
+		modified = true
+	}
+
+	if modified {
+		if err := l.SaveProject(project); err != nil {
+			return fmt.Errorf("saving repaired project: %w", err)
+		}
+	}
+
+	return nil
+}
+
+// repairConfigurationChange validates and fixes configuration data
+func (l *LocalDB) repairConfigurationChange(change *PendingChange) error {
+	config, err := l.GetConfigurationByUUID(change.EntityUUID)
+	if err != nil {
+		return fmt.Errorf("configuration not found locally: %w", err)
+	}
+
+	modified := false
+
+	// Check if referenced project exists
+	if config.ProjectUUID != nil && *config.ProjectUUID != "" {
+		_, err := l.GetProjectByUUID(*config.ProjectUUID)
+		if err != nil {
+			// Project doesn't exist locally - use default system project
+			systemProject, sysErr := l.EnsureDefaultProject(config.OriginalUsername)
+			if sysErr != nil {
+				return fmt.Errorf("getting system project: %w", sysErr)
+			}
+			config.ProjectUUID = &systemProject.UUID
+			modified = true
+		}
+	}
+
+	if modified {
+		if err := l.SaveConfiguration(config); err != nil {
+			return fmt.Errorf("saving repaired configuration: %w", err)
+		}
+	}
+
+	return nil
+}
+
 // GetRemoteMigrationApplied returns a locally applied remote migration by ID.
 func (l *LocalDB) GetRemoteMigrationApplied(id string) (*LocalRemoteMigrationApplied, error) {
 	var migration LocalRemoteMigrationApplied