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/emoji-regex/es2015/RGI_Emoji.d.ts

@@ -0,0 +1,5 @@
+declare module 'emoji-regex/es2015/RGI_Emoji' {
+  function emojiRegex(): RegExp;
+
+  export = emojiRegex;
+}

node_modules/emoji-regex/es2015/index.d.ts

@@ -0,0 +1,5 @@
+declare module 'emoji-regex/es2015' {
+  function emojiRegex(): RegExp;
+
+  export = emojiRegex;
+}

node_modules/emoji-regex/es2015/text.d.ts

@@ -0,0 +1,5 @@
+declare module 'emoji-regex/es2015/text' {
+  function emojiRegex(): RegExp;
+
+  export = emojiRegex;
+}