refactor(chat): align chat header and input bar with Dart source

src/app/chat/components/chat-screen.tsx

@@ -24,6 +24,8 @@ import Image from "next/image";
 import { useChatDispatch, useChatState } from "@/stores/chat/chat-context";
 import { GuestChatQuota } from "@/stores/chat/chat-types";
 
+import { MobileShell } from "@/app/_components/core/mobile-shell";
+
 import { BrowserHintOverlay } from "./browser-hint-overlay";
 import { ChatArea } from "./chat-area";
 import { ChatHeader } from "./chat-header";
@@ -76,42 +78,44 @@ export function ChatScreen() {
   }, [state.guestRemainingQuota, state.isGuest]);
 
   return (
-    <div className={styles.shell}>
-      {/* 背景图（与原 Dart MobileLayout 一致） */}
-      <div className={styles.background}>
-        <Image
-          src="/images/chat/bg-chatpage.png"
-          alt=""
-          fill
-          priority
-          sizes="(max-width: 500px) 100vw, 500px"
+    <MobileShell>
+      <div className={styles.shell}>
+        {/* 背景图（与原 Dart MobileLayout 一致） */}
+        <div className={styles.background}>
+          <Image
+            src="/images/chat/bg-chatpage.png"
+            alt=""
+            fill
+            priority
+            sizes="(max-width: 500px) 100vw, 500px"
+          />
+        </div>
+
+        <div className={styles.layout}>
+          <ChatHeader isGuest={state.isGuest} />
+
+          <ChatArea
+            messages={state.messages}
+            isReplyingAI={state.isReplyingAI}
+            isGuest={state.isGuest}
+          />
+
+          <ChatInputBar disabled={state.isReplyingAI} />
+        </div>
+
+        {/* 浏览器提示（应用内浏览器检测） */}
+        <BrowserHintOverlay />
+
+        {/* PWA 安装提示触发器（无可见 UI，3.5s 后弹 dialog） */}
+        <PwaInstallOverlay />
+
+        {/* 配额告警弹窗 */}
+        <QuotaDialog
+          open={quotaDialogOpen}
+          onClose={() => setQuotaDialogOpen(false)}
+          isExhausted={quotaExhausted}
         />
       </div>
-
-      <div className={styles.layout}>
-        <ChatHeader isGuest={state.isGuest} />
-
-        <ChatArea
-          messages={state.messages}
-          isReplyingAI={state.isReplyingAI}
-          isGuest={state.isGuest}
-        />
-
-        <ChatInputBar disabled={state.isReplyingAI} />
-      </div>
-
-      {/* 浏览器提示（应用内浏览器检测） */}
-      <BrowserHintOverlay />
-
-      {/* PWA 安装提示触发器（无可见 UI，3.5s 后弹 dialog） */}
-      <PwaInstallOverlay />
-
-      {/* 配额告警弹窗 */}
-      <QuotaDialog
-        open={quotaDialogOpen}
-        onClose={() => setQuotaDialogOpen(false)}
-        isExhausted={quotaExhausted}
-      />
-    </div>
+    </MobileShell>
   );
 }