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/reusify/eslint.config.js

@@ -0,0 +1,14 @@
+'use strict'
+
+const base = require('neostandard')({})
+
+module.exports = [
+  ...base,
+  {
+    name: 'old-standard',
+    rules: {
+      'no-var': 'off',
+      'object-shorthand': 'off',
+    }
+  }
+]