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/adapters/fs.d.ts

@@ -0,0 +1,20 @@
+import type * as fsStat from '@nodelib/fs.stat';
+import type { Dirent, ErrnoException } from '../types';
+export interface ReaddirAsynchronousMethod {
+    (filepath: string, options: {
+        withFileTypes: true;
+    }, callback: (error: ErrnoException | null, files: Dirent[]) => void): void;
+    (filepath: string, callback: (error: ErrnoException | null, files: string[]) => void): void;
+}
+export interface ReaddirSynchronousMethod {
+    (filepath: string, options: {
+        withFileTypes: true;
+    }): Dirent[];
+    (filepath: string): string[];
+}
+export declare type FileSystemAdapter = fsStat.FileSystemAdapter & {
+    readdir: ReaddirAsynchronousMethod;
+    readdirSync: ReaddirSynchronousMethod;
+};
+export declare const FILE_SYSTEM_ADAPTER: FileSystemAdapter;
+export declare function createFileSystemAdapter(fsMethods?: Partial<FileSystemAdapter>): FileSystemAdapter;