fix(auth): remove username from password verification payload and fix proxy refresh handler

- Remove redundant username field from password verification payload in CodexAPIAuth
- Update proxy refresh button to use arrow function for proper event handling
- Simplify authentication flow by eliminating unnecessary email parameter in password verification request

frontend/src/pages/CodexProxyConfig.tsx

@@ -435,7 +435,7 @@ export default function CodexProxyConfig() {
                 <div className="flex gap-2">
                     <Button
                         variant="outline"
-                        onClick={fetchProxies}
+                        onClick={() => fetchProxies()}
                         icon={<RefreshCw className="h-4 w-4" />}
                     >
                         刷新