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/@vitest/utils/dist/error.d.ts

@@ -0,0 +1,11 @@
+import { D as DiffOptions } from './types-9l4niLY8.js';
+import 'pretty-format';
+
+declare function serializeError(val: any, seen?: WeakMap<WeakKey, any>): any;
+declare function processError(err: any, diffOptions?: DiffOptions): any;
+declare function replaceAsymmetricMatcher(actual: any, expected: any, actualReplaced?: WeakSet<WeakKey>, expectedReplaced?: WeakSet<WeakKey>): {
+    replacedActual: any;
+    replacedExpected: any;
+};
+
+export { processError, replaceAsymmetricMatcher, serializeError };