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/slice.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 Slice = createLucideIcon("Slice", [
+  ["path", { d: "m8 14-6 6h9v-3", key: "zo3j9a" }],
+  ["path", { d: "M18.37 3.63 8 14l3 3L21.37 6.63a2.12 2.12 0 1 0-3-3Z", key: "1dzx0j" }]
+]);
+
+export { Slice as default };
+//# sourceMappingURL=slice.js.map