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/ice-cream-2.js

@@ -0,0 +1,23 @@
+/**
+ * @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 IceCream2 = createLucideIcon("IceCream2", [
+  [
+    "path",
+    {
+      d: "M12 17c5 0 8-2.69 8-6H4c0 3.31 3 6 8 6Zm-4 4h8m-4-3v3M5.14 11a3.5 3.5 0 1 1 6.71 0",
+      key: "g86ewz"
+    }
+  ],
+  ["path", { d: "M12.14 11a3.5 3.5 0 1 1 6.71 0", key: "4k3m1s" }],
+  ["path", { d: "M15.5 6.5a3.5 3.5 0 1 0-7 0", key: "zmuahr" }]
+]);
+
+export { IceCream2 as default };
+//# sourceMappingURL=ice-cream-2.js.map