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/postcss-js/index.js

@@ -0,0 +1,11 @@
+let async = require('./async')
+let objectify = require('./objectifier')
+let parse = require('./parser')
+let sync = require('./sync')
+
+module.exports = {
+  objectify,
+  parse,
+  async,
+  sync
+}