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/config/flat/recommended.js

@@ -0,0 +1,26 @@
+/**
+ * The basics.
+ * @type {Object}
+ */
+module.exports = {
+  rules: {
+    // analysis/correctness
+    'import/no-unresolved': 'error',
+    'import/named': 'error',
+    'import/namespace': 'error',
+    'import/default': 'error',
+    'import/export': 'error',
+
+    // red flags (thus, warnings)
+    'import/no-named-as-default': 'warn',
+    'import/no-named-as-default-member': 'warn',
+    'import/no-duplicates': 'warn',
+  },
+
+  // need all these for parsing dependencies (even if _your_ code doesn't need
+  // all of them)
+  languageOptions: {
+    ecmaVersion: 2018,
+    sourceType: 'module',
+  },
+};