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/folder-dot.js

@@ -0,0 +1,22 @@
+/**
+ * @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 FolderDot = createLucideIcon("FolderDot", [
+  [
+    "path",
+    {
+      d: "M4 20h16a2 2 0 0 0 2-2V8a2 2 0 0 0-2-2h-7.93a2 2 0 0 1-1.66-.9l-.82-1.2A2 2 0 0 0 7.93 3H4a2 2 0 0 0-2 2v13c0 1.1.9 2 2 2Z",
+      key: "1fr9dc"
+    }
+  ],
+  ["circle", { cx: "12", cy: "13", r: "1", key: "49l61u" }]
+]);
+
+export { FolderDot as default };
+//# sourceMappingURL=folder-dot.js.map