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/bigint.js

@@ -0,0 +1,7 @@
+import { truncate, truncator } from './helpers'
+
+export default function inspectBigInt(number, options) {
+  let nums = truncate(number.toString(), options.truncate - 1)
+  if (nums !== truncator) nums += 'n'
+  return options.stylize(nums, 'bigint')
+}