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/axios/lib/helpers/isURLSameOrigin.js

@@ -0,0 +1,16 @@
+import platform from '../platform/index.js';
+
+export default platform.hasStandardBrowserEnv
+  ? ((origin, isMSIE) => (url) => {
+      url = new URL(url, platform.origin);
+
+      return (
+        origin.protocol === url.protocol &&
+        origin.host === url.host &&
+        (isMSIE || origin.port === url.port)
+      );
+    })(
+      new URL(platform.origin),
+      platform.navigator && /(msie|trident)/i.test(platform.navigator.userAgent)
+    )
+  : () => true;