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/autoprefixer/lib/hacks/image-set.js

@@ -0,0 +1,18 @@
+let Value = require('../value')
+
+class ImageSet extends Value {
+  /**
+   * Use non-standard name for WebKit and Firefox
+   */
+  replace(string, prefix) {
+    let fixed = super.replace(string, prefix)
+    if (prefix === '-webkit-') {
+      fixed = fixed.replace(/("[^"]+"|'[^']+')(\s+\d+\w)/gi, 'url($1)$2')
+    }
+    return fixed
+  }
+}
+
+ImageSet.names = ['image-set']
+
+module.exports = ImageSet