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/fs-extra/lib/mkdirs/index.js

@@ -0,0 +1,14 @@
+'use strict'
+const u = require('universalify').fromPromise
+const { makeDir: _makeDir, makeDirSync } = require('./make-dir')
+const makeDir = u(_makeDir)
+
+module.exports = {
+  mkdirs: makeDir,
+  mkdirsSync: makeDirSync,
+  // alias
+  mkdirp: makeDir,
+  mkdirpSync: makeDirSync,
+  ensureDir: makeDir,
+  ensureDirSync: makeDirSync
+}