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/tangent.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 Tangent = createLucideIcon("Tangent", [
+  ["circle", { cx: "17", cy: "4", r: "2", key: "y5j2s2" }],
+  ["path", { d: "M15.59 5.41 5.41 15.59", key: "l0vprr" }],
+  ["circle", { cx: "4", cy: "17", r: "2", key: "9p4efm" }],
+  ["path", { d: "M12 22s-4-9-1.5-11.5S22 12 22 12", key: "1twk4o" }]
+]);
+
+export { Tangent as default };
+//# sourceMappingURL=tangent.js.map