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/promise.js

@@ -0,0 +1,16 @@
+let getPromiseValue = () => 'Promise{…}'
+try {
+  const { getPromiseDetails, kPending, kRejected } = process.binding('util')
+  if (Array.isArray(getPromiseDetails(Promise.resolve()))) {
+    getPromiseValue = (value, options) => {
+      const [state, innerValue] = getPromiseDetails(value)
+      if (state === kPending) {
+        return 'Promise{<pending>}'
+      }
+      return `Promise${state === kRejected ? '!' : ''}{${options.inspect(innerValue, options)}}`
+    }
+  }
+} catch (notNode) {
+  /* ignore */
+}
+export default getPromiseValue