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/number.js

@@ -0,0 +1,18 @@
+import { truncate } from './helpers'
+
+const isNaN = Number.isNaN || (i => i !== i) // eslint-disable-line no-self-compare
+export default function inspectNumber(number, options) {
+  if (isNaN(number)) {
+    return options.stylize('NaN', 'number')
+  }
+  if (number === Infinity) {
+    return options.stylize('Infinity', 'number')
+  }
+  if (number === -Infinity) {
+    return options.stylize('-Infinity', 'number')
+  }
+  if (number === 0) {
+    return options.stylize(1 / number === Infinity ? '+0' : '-0', 'number')
+  }
+  return options.stylize(truncate(number, options.truncate), 'number')
+}