added backend and 2 endpoints fetch

backend/internal/category/GetAllCategories.go

@@ -0,0 +1,33 @@
+package category
+
+import "backend/model"
+
+func GetAllCategories() ([]model.Category, error) {
+	return []model.Category{
+		{
+			ID:    "1",
+			Title: "Electronics",
+			Icon:  "😀",
+		},
+		{
+			ID:    "2",
+			Title: "Clothing",
+			Icon:  "😁",
+		},
+		{
+			ID:    "3",
+			Title: "Books",
+			Icon:  "😂",
+			Subcategories: []model.Subcategory{
+				{
+					ID:    "1",
+					Title: "Fiction",
+				},
+				{
+					ID:    "2",
+					Title: "Non-Fiction",
+				},
+			},
+		},
+	}, nil
+}