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/loupe/lib/set.js

@@ -0,0 +1,16 @@
+import { inspectList } from './helpers'
+
+// IE11 doesn't support `Array.from(set)`
+function arrayFromSet(set) {
+  const values = []
+  set.forEach(value => {
+    values.push(value)
+  })
+  return values
+}
+
+export default function inspectSet(set, options) {
+  if (set.size === 0) return 'Set{}'
+  options.truncate -= 7
+  return `Set{ ${inspectList(arrayFromSet(set), options)} }`
+}