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/fork-ts-checker-webpack-plugin/lib/issue/IssueConfiguration.d.ts

@@ -0,0 +1,8 @@
+import webpack from 'webpack';
+import { IssuePredicate } from './IssuePredicate';
+import { IssueOptions } from './IssueOptions';
+interface IssueConfiguration {
+    predicate: IssuePredicate;
+}
+declare function createIssueConfiguration(compiler: webpack.Compiler, options: IssueOptions | undefined): IssueConfiguration;
+export { IssueConfiguration, createIssueConfiguration };