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/appearance.js

@@ -0,0 +1,23 @@
+let Declaration = require('../declaration')
+let utils = require('../utils')
+
+class Appearance extends Declaration {
+  constructor(name, prefixes, all) {
+    super(name, prefixes, all)
+
+    if (this.prefixes) {
+      this.prefixes = utils.uniq(
+        this.prefixes.map(i => {
+          if (i === '-ms-') {
+            return '-webkit-'
+          }
+          return i
+        })
+      )
+    }
+  }
+}
+
+Appearance.names = ['appearance']
+
+module.exports = Appearance