src->memory folder added

frontend/src/memory/data/dummy-data.js

+import Category from "../models/category";
+
+export const CATEGORIES = [
+    new Category('1', 'Memo', 'https://cdn.pixabay.com/photo/2014/09/21/21/31/flowers-455591_960_720.jpg'),
+    new Category('2', 'Inorder', 'https://cdn.pixabay.com/photo/2019/02/22/19/03/numbers-4014181_960_720.jpg'),
+    new Category('3', 'Shapes', 'https://cdn.pixabay.com/photo/2018/08/22/12/38/color-3623523_960_720.jpg'),
+    new Category('4', 'Memo', 'https://cdn.pixabay.com/photo/2014/09/21/21/31/flowers-455591_960_720.jpg'),
+]
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frontend/src/memory/models/category.js

+class Category{
+    constructor(id, title, url){
+        this.id = id,
+        this.title = title,
+        this.url = url
+    }
+}
+
+export default Category;
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