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/immer/dist/utils/env.d.ts

@@ -0,0 +1,23 @@
+export declare const hasMap: boolean;
+export declare const hasSet: boolean;
+export declare const hasProxies: boolean;
+/**
+ * The sentinel value returned by producers to replace the draft with undefined.
+ */
+export declare const NOTHING: Nothing;
+/**
+ * To let Immer treat your class instances as plain immutable objects
+ * (albeit with a custom prototype), you must define either an instance property
+ * or a static property on each of your custom classes.
+ *
+ * Otherwise, your class instance will never be drafted, which means it won't be
+ * safe to mutate in a produce callback.
+ */
+export declare const DRAFTABLE: unique symbol;
+export declare const DRAFT_STATE: unique symbol;
+export declare const iteratorSymbol: typeof Symbol.iterator;
+/** Use a class type for `nothing` so its type is unique */
+export declare class Nothing {
+    private _;
+}
+//# sourceMappingURL=env.d.ts.map