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/sass-loader/dist/SassWarning.js

@@ -0,0 +1,25 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = void 0;
+
+class SassWarning extends Error {
+  constructor(warning, options) {
+    super(warning);
+    this.name = "SassWarning";
+    this.hideStack = true;
+
+    if (options.span) {
+      this.loc = {
+        line: options.span.start.line,
+        column: options.span.start.column
+      };
+    }
+  }
+
+}
+
+var _default = SassWarning;
+exports.default = _default;