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/lucide-react/dist/esm/icons/mouse-pointer-square.js

@@ -0,0 +1,16 @@
+/**
+ * @license lucide-react v0.303.0 - ISC
+ *
+ * This source code is licensed under the ISC license.
+ * See the LICENSE file in the root directory of this source tree.
+ */
+
+import createLucideIcon from '../createLucideIcon.js';
+
+const MousePointerSquare = createLucideIcon("MousePointerSquare", [
+  ["path", { d: "M21 11V5a2 2 0 0 0-2-2H5a2 2 0 0 0-2 2v14a2 2 0 0 0 2 2h6", key: "14rsvq" }],
+  ["path", { d: "m12 12 4 10 1.7-4.3L22 16Z", key: "64ilsv" }]
+]);
+
+export { MousePointerSquare as default };
+//# sourceMappingURL=mouse-pointer-square.js.map