Add a synthetic "All" category to getappcategories

The mobile app needs an "All" tile to browse every product regardless of
category. Rather than inserting a real app_category row (which would break
once any category-scoped product filter treats it as an actual, empty
category), the service now prepends a synthetic entry with categoryid=0 —
reusing the "0 = no category filter" convention GetAllProducts already
implements in FetchFilteredProducts.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

services/utilsService.go

@@ -48,5 +48,25 @@ func (s *utilsService) GetAppConfig(configID int) (models.Appconfig, error) {
 }
 
 func (s *utilsService) GetAppCategory() ([]models.AppCategory, error) {
-	return s.repo.GetAppCategory()
+	categories, err := s.repo.GetAppCategory()
+	if err != nil {
+		return nil, err
+	}
+
+	// "All" is a synthetic pseudo-category, not a real app_category row — it
+	// must never be inserted into app_category itself, since product-listing
+	// filters (e.g. ProductController.GetAllProducts) already treat
+	// categoryid=0 as "no category filter". Keeping this row's id at 0 reuses
+	// that existing convention instead of adding a new one.
+	all := models.AppCategory{
+		Categoryid:   0,
+		Categoryname: "All",
+		Categorytype: 7,
+		Sortorder:    0,
+		Crossaxis:    1,
+		Mainaxis:     1,
+		Status:       "Active",
+	}
+
+	return append([]models.AppCategory{all}, categories...), nil
 }