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/@surma/rollup-plugin-off-main-thread/tests/fixtures/assets-in-worker/rollup.config.js

@@ -0,0 +1,25 @@
+const MARKER = "my-special-import";
+module.exports = (config, outputOptions, omt) => {
+  config.plugins = [
+    omt(),
+    {
+      resolveId(id) {
+        if (id !== MARKER) {
+          return;
+        }
+        return id;
+      },
+      load(id) {
+        if (id !== MARKER) {
+          return;
+        }
+        const referenceId = this.emitFile({
+          type: "asset",
+          name: "my-asset.bin",
+          source: "assetcontent"
+        });
+        return `export default import.meta.ROLLUP_FILE_URL_${referenceId}`;
+      }
+    }
+  ];
+};