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/workbox-build/.ncurc.js

@@ -0,0 +1,19 @@
+/*
+  Copyright 2020 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+
+// We use `npx npm-check-updates` to find updates to dependencies.
+// Some dependencies have breaking changes that we can't resolve.
+// This config file excludes those dependencies from the checks
+// until we're able to remediate our code to deal with them.
+module.exports = {
+  reject: [
+    // joi v16 is the last release to support Node v10:
+    // https://github.com/sideway/joi/issues/2262
+    '@hapi/joi',
+  ],
+};