fix: 批量修正 external 字面量

src/components/MemoryUsageIndicator.tsx

@@ -7,7 +7,7 @@ export function MemoryUsageIndicator(): React.ReactNode {
   // the hook means the 10s polling interval is never set up in external builds.
   // USER_TYPE is a build-time constant, so the hook call below is either always
   // reached or dead-code-eliminated — never conditional at runtime.
-  if (("external" as string) !== 'ant') {
+  if ((process.env.USER_TYPE) !== 'ant') {
     return null;
   }