fix(chat): restore image message scroll anchor

src/app/chat/components/message-bubble.tsx

@@ -49,7 +49,11 @@ export function MessageBubble({
 
   if (isFromAI) {
     return (
-      <div className={styles.bubbleRowAi} aria-label="AI message">
+      <div
+        className={styles.bubbleRowAi}
+        data-chat-message-id={messageId}
+        aria-label="AI message"
+      >
         <MessageAvatar isFromAI={true} />
         <div style={{ width: 8 }} />
         <MessageContent
@@ -73,7 +77,11 @@ export function MessageBubble({
   }
 
   return (
-    <div className={styles.bubbleRowUser} aria-label="User message">
+    <div
+      className={styles.bubbleRowUser}
+      data-chat-message-id={messageId}
+      aria-label="User message"
+    >
       <div style={{ width: 43 }} /> {/* 占位 */}
       <MessageContent
         content={content}