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/readBlob.js

@@ -0,0 +1,15 @@
+const { asyncIterator } = Symbol;
+
+const readBlob = async function* (blob) {
+  if (blob.stream) {
+    yield* blob.stream();
+  } else if (blob.arrayBuffer) {
+    yield await blob.arrayBuffer();
+  } else if (blob[asyncIterator]) {
+    yield* blob[asyncIterator]();
+  } else {
+    yield blob;
+  }
+};
+
+export default readBlob;