Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/memfs/lib/volume-localstorage.d.ts

@@ -0,0 +1,14 @@
+import { Volume } from './volume';
+export interface IStore {
+    setItem(key: string, json: any): any;
+    getItem(key: string): any;
+    removeItem(key: string): any;
+}
+export declare class ObjectStore {
+    obj: object;
+    constructor(obj: any);
+    setItem(key: string, json: any): void;
+    getItem(key: string): any;
+    removeItem(key: string): void;
+}
+export declare function createVolume(namespace: string, LS?: IStore | object): new (...args: any[]) => Volume;