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/percent-square.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 PercentSquare = createLucideIcon("PercentSquare", [
+  ["rect", { width: "18", height: "18", x: "3", y: "3", rx: "2", key: "afitv7" }],
+  ["path", { d: "m15 9-6 6", key: "1uzhvr" }],
+  ["path", { d: "M9 9h.01", key: "1q5me6" }],
+  ["path", { d: "M15 15h.01", key: "lqbp3k" }]
+]);
+
+export { PercentSquare as default };
+//# sourceMappingURL=percent-square.js.map