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/eslint-plugin-import/docs/rules/export.md

@@ -0,0 +1,37 @@
+# import/export
+
+💼 This rule is enabled in the following configs: ❗ `errors`, ☑️ `recommended`.
+
+<!-- end auto-generated rule header -->
+
+Reports funny business with exports, like repeated exports of names or defaults.
+
+## Rule Details
+
+```js
+export default class MyClass { /*...*/ } // Multiple default exports.
+
+function makeClass() { return new MyClass(...arguments) }
+
+export default makeClass // Multiple default exports.
+```
+
+or
+
+```js
+export const foo = function () { /*...*/ } // Multiple exports of name 'foo'.
+
+function bar() { /*...*/ }
+export { bar as foo } // Multiple exports of name 'foo'.
+```
+
+In the case of named/default re-export, all `n` re-exports will be reported,
+as at least `n-1` of them are clearly mistakes, but it is not clear which one
+(if any) is intended. Could be the result of copy/paste, code duplication with
+intent to rename, etc.
+
+## Further Reading
+
+ - Lee Byron's [ES7] export proposal
+
+[ES7]: https://github.com/leebyron/ecmascript-more-export-from