fix(chat): handle guest total limit

src/app/chat/chat-screen.tsx

@@ -43,10 +43,15 @@ export function ChatScreen() {
   // isGuest 派生（chat-screen 是唯一知道这个值的地方 —— chat 机器无 isGuest 字段）
   const isGuest = deriveIsGuest(authState.loginStatus);
 
-  // 消息数量限制由后端统一返回 blocked/daily_limit，前端不再处理本地额度。
-  const showDailyLimitBanner =
+  // 消息数量限制由后端统一返回 blocked，前端不再处理本地额度。
+  const showMessageLimitBanner =
     state.paywallTriggered &&
-    state.paywallReason === "daily_limit";
+    (state.paywallReason === "daily_limit" ||
+      state.paywallReason === "total_limit");
+  const messageLimitTitle =
+    state.paywallReason === "total_limit"
+      ? "The limit for free chat times\nhas been reached"
+      : undefined;
   const showPhotoPaywallBanner =
     state.paywallTriggered && state.paywallReason === "photo_paywall";
   const showPrivatePaywallBanner =
@@ -168,8 +173,9 @@ export function ChatScreen() {
             />
           ) : null}
 
-          {showDailyLimitBanner ? (
+          {showMessageLimitBanner ? (
             <ChatQuotaExhaustedBanner
+              title={messageLimitTitle}
             />
           ) : (
             <ChatInputBar disabled={state.isReplyingAI} />