fix: 用户消息靠右对齐 - 移除flex: 1让内容自适应宽度

src/pages/chat/components/messages/MessageItem.tsx

@@ -125,7 +125,7 @@ export default function MessageItem(props: {
       ) : (
         <div style={{ display: 'flex', gap: 12, alignItems: 'flex-start', justifyContent: 'flex-end' }}>
           {/* 用户: 头像在右侧，内容在左侧（靠右对齐） */}
-          <div style={{ flex: 1, minWidth: 0, maxWidth: '78%', display: 'flex', flexDirection: 'column', alignItems: 'flex-end' }}>
+          <div style={{ maxWidth: '78%', display: 'flex', flexDirection: 'column', alignItems: 'flex-end' }}>
             <div style={{
               display: 'flex',
               alignItems: 'center',