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/user-plus.js

@@ -0,0 +1,18 @@
+/**
+ * @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 UserPlus = createLucideIcon("UserPlus", [
+  ["path", { d: "M16 21v-2a4 4 0 0 0-4-4H6a4 4 0 0 0-4 4v2", key: "1yyitq" }],
+  ["circle", { cx: "9", cy: "7", r: "4", key: "nufk8" }],
+  ["line", { x1: "19", x2: "19", y1: "8", y2: "14", key: "1bvyxn" }],
+  ["line", { x1: "22", x2: "16", y1: "11", y2: "11", key: "1shjgl" }]
+]);
+
+export { UserPlus as default };
+//# sourceMappingURL=user-plus.js.map