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/@bcoe/v8-coverage/dist/lib/ascii.d.ts

@@ -0,0 +1,12 @@
+import { RangeCov } from "./types";
+interface ReadonlyRangeTree {
+    readonly start: number;
+    readonly end: number;
+    readonly count: number;
+    readonly children: ReadonlyRangeTree[];
+}
+export declare function emitForest(trees: ReadonlyArray<ReadonlyRangeTree>): string;
+export declare function emitForestLines(trees: ReadonlyArray<ReadonlyRangeTree>): string[];
+export declare function parseFunctionRanges(text: string, offsetMap: Map<number, number>): RangeCov[];
+export declare function parseOffsets(text: string): Map<number, number>;
+export {};