fix: SW 缓存导致页面不更新 — fetch 绕过 HTTP 缓存 + hydration 闪屏修复

- sw.js: HTML fetch 加 cache:"no-cache"，避免从浏览器缓存拿旧页面
- ServiceWorkerRegistrar: 注册时 updateViaCache:"none"，确保 SW 自身及时更新
- blindbox/page: 增加 hydrated 状态，防止 SSR/CSR 内容不一致导致闪屏

src/app/blindbox/page.tsx

@@ -31,6 +31,7 @@ interface RoomSummary {
 
 export default function BlindboxLobbyPage() {
   const router = useRouter();
+  const [hydrated, setHydrated] = useState(false);
   const [loggedIn, setLoggedIn] = useState(false);
   const [profile, setProfile] = useState<UserProfile | null>(null);
   const [showAuth, setShowAuth] = useState(false);
@@ -50,6 +51,7 @@ export default function BlindboxLobbyPage() {
     if (registered) {
       setProfile(getCachedProfile());
     }
+    setHydrated(true);
   }, []);
 
   useEffect(() => {
@@ -207,7 +209,9 @@ export default function BlindboxLobbyPage() {
       </motion.div>
 
       <AnimatePresence mode="wait">
-        {!loggedIn ? (
+        {!hydrated || (loggedIn && loading) ? (
+          <BlindboxListSkeleton />
+        ) : !loggedIn ? (
           /* ============ Layer 1: Unauthenticated — Login CTA ============ */
           <motion.div
             key="intro"
@@ -230,8 +234,6 @@ export default function BlindboxLobbyPage() {
               仅需用户名 + 密码，10 秒注册
             </p>
           </motion.div>
-        ) : loading ? (
-          <BlindboxListSkeleton />
         ) : loadError ? (
           <motion.div
             key="load-error"

src/components/ServiceWorkerRegistrar.tsx

@@ -5,7 +5,7 @@ import { useEffect } from "react";
 export default function ServiceWorkerRegistrar() {
   useEffect(() => {
     if ("serviceWorker" in navigator) {
-      navigator.serviceWorker.register("/sw.js").catch(() => {});
+      navigator.serviceWorker.register("/sw.js", { updateViaCache: "none" }).catch(() => {});
     }
   }, []);