Refine VPN client instructions and subscription refresh flow

src/server/subscription.js

@@ -160,13 +160,13 @@ async function requestSubscription(url) {
   return response;
 }
 
-export async function fetchSubscriptionInfo(url) {
-  const response = await requestSubscription(url);
-  await response.body?.cancel();
-  return {
-    userInfo: parseUserInfo(response.headers.get('subscription-userinfo')),
-    fetchedAt: new Date().toISOString(),
-  };
+export function selectRefreshedServer(currentTag, servers) {
+  const selectedTag = String(currentTag || '').trim();
+  if (!selectedTag) return '';
+
+  return servers.find((server) => String(server.tag || '').trim() === selectedTag)?.tag
+    || servers[0]?.tag
+    || '';
 }
 
 export async function fetchSubscription(url) {