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/function-square.js

@@ -0,0 +1,17 @@
+/**
+ * @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 FunctionSquare = createLucideIcon("FunctionSquare", [
+  ["rect", { width: "18", height: "18", x: "3", y: "3", rx: "2", ry: "2", key: "1m3agn" }],
+  ["path", { d: "M9 17c2 0 2.8-1 2.8-2.8V10c0-2 1-3.3 3.2-3", key: "m1af9g" }],
+  ["path", { d: "M9 11.2h5.7", key: "3zgcl2" }]
+]);
+
+export { FunctionSquare as default };
+//# sourceMappingURL=function-square.js.map