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/dom-accessibility-api/dist/polyfills/SetLike.d.ts

@@ -0,0 +1,14 @@
+declare global {
+    class Set<T> {
+        constructor(items?: T[]);
+        add(value: T): this;
+        clear(): void;
+        delete(value: T): boolean;
+        forEach(callbackfn: (value: T, value2: T, set: Set<T>) => void, thisArg?: unknown): void;
+        has(value: T): boolean;
+        readonly size: number;
+    }
+}
+declare const _default: typeof Set;
+export default _default;
+//# sourceMappingURL=SetLike.d.ts.map