FIX[BE]Lock chickins, accumulate pending qty, use qty key

internal/modules/production/chickins/repositories/project_chickin.repository.go

@@ -68,11 +68,17 @@ func (r *ChickinRepositoryImpl) GetByProjectFlockKandangID(ctx context.Context,
 // GetByProjectFlockKandangIDForUpdate locks chickin rows to prevent race condition
 func (r *ChickinRepositoryImpl) GetByProjectFlockKandangIDForUpdate(ctx context.Context, projectFlockKandangID uint) ([]entity.ProjectChickin, error) {
 	var chickins []entity.ProjectChickin
+	// CRITICAL: Use FOR UPDATE to lock rows and prevent concurrent chickin requests
+	// This ensures that simultaneous requests wait for each other and read consistent pending_qty
 	err := r.db.WithContext(ctx).
-		Where("project_flock_kandang_id = ?", projectFlockKandangID).
-		Order("created_at DESC").
-		Find(&chickins).
-		Error
+		Raw(`
+			SELECT * FROM project_chickins
+			WHERE project_flock_kandang_id = ?
+			AND deleted_at IS NULL
+			ORDER BY created_at DESC
+			FOR UPDATE
+		`, projectFlockKandangID).
+		Scan(&chickins).Error
 	if err != nil {
 		return nil, err
 	}