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/bar-chart-3.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 BarChart3 = createLucideIcon("BarChart3", [
+  ["path", { d: "M3 3v18h18", key: "1s2lah" }],
+  ["path", { d: "M18 17V9", key: "2bz60n" }],
+  ["path", { d: "M13 17V5", key: "1frdt8" }],
+  ["path", { d: "M8 17v-3", key: "17ska0" }]
+]);
+
+export { BarChart3 as default };
+//# sourceMappingURL=bar-chart-3.js.map