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/jiti/dist/utils.d.ts

@@ -0,0 +1,8 @@
+import type { PackageJson } from "pkg-types";
+export declare function getCacheDir(): string;
+export declare function isDir(filename: string): boolean;
+export declare function isWritable(filename: string): boolean;
+export declare function md5(content: string, len?: number): string;
+export declare function detectLegacySyntax(code: string): RegExpMatchArray | null;
+export declare function isObject(val: any): boolean;
+export declare function readNearestPackageJSON(path: string): PackageJson | undefined;