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/index.d.ts

@@ -0,0 +1,33 @@
+import { ESLint, Linter, Rule } from 'eslint';
+
+declare const plugin: ESLint.Plugin & {
+  meta: {
+    name: string;
+    version: string;
+  };
+  configs: {
+    'recommended': Linter.LegacyConfig;
+    'errors': Linter.LegacyConfig;
+    'warnings': Linter.LegacyConfig;
+    'stage-0': Linter.LegacyConfig;
+    'react': Linter.LegacyConfig;
+    'react-native': Linter.LegacyConfig;
+    'electron': Linter.LegacyConfig;
+    'typescript': Linter.LegacyConfig;
+  };
+  flatConfigs: {
+    'recommended': Linter.FlatConfig;
+    'errors': Linter.FlatConfig;
+    'warnings': Linter.FlatConfig;
+    'stage-0': Linter.FlatConfig;
+    'react': Linter.FlatConfig;
+    'react-native': Linter.FlatConfig;
+    'electron': Linter.FlatConfig;
+    'typescript': Linter.FlatConfig;
+  };
+  rules: {
+    [key: string]: Rule.RuleModule;
+  };
+};
+
+export = plugin;