feat(frontend): add API client, layout, and routing

- Create Axios-based API client with sources, jobs, and dashboard endpoints
- Add responsive Layout component with navigation sidebar
- Set up React Router with Dashboard, Backups, and Settings routes
- Configure TanStack Query provider with default options
- Use lucide-react for navigation icons

frontend/node_modules/@nodelib/fs.scandir/out/index.d.ts

@@ -0,0 +1,12 @@
+import type { FileSystemAdapter, ReaddirAsynchronousMethod, ReaddirSynchronousMethod } from './adapters/fs';
+import * as async from './providers/async';
+import Settings, { Options } from './settings';
+import type { Dirent, Entry } from './types';
+declare type AsyncCallback = async.AsyncCallback;
+declare function scandir(path: string, callback: AsyncCallback): void;
+declare function scandir(path: string, optionsOrSettings: Options | Settings, callback: AsyncCallback): void;
+declare namespace scandir {
+    function __promisify__(path: string, optionsOrSettings?: Options | Settings): Promise<Entry[]>;
+}
+declare function scandirSync(path: string, optionsOrSettings?: Options | Settings): Entry[];
+export { scandir, scandirSync, Settings, AsyncCallback, Dirent, Entry, FileSystemAdapter, ReaddirAsynchronousMethod, ReaddirSynchronousMethod, Options };