feat: 全站评论开关，并统一后台表单控件

关闭评论后前台隐藏评论能力；外观/设置/公告改用 AdminField 与 Stepper。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/app/u/[id]/UserProfileContent.tsx

@@ -16,6 +16,7 @@ export default function UserProfileContent({
   commentData,
   commentError,
   page,
+  allowComments = true,
 }: {
   userId: string;
   profile: UserProfile;
@@ -23,6 +24,7 @@ export default function UserProfileContent({
   commentData: UserCommentsResponse | null;
   commentError: boolean;
   page: number;
+  allowComments?: boolean;
 }) {
   return (
     <div>
@@ -50,9 +52,11 @@ export default function UserProfileContent({
                   </h2>
                   <div className="flex items-center gap-4 meta text-[12px]">
                     <span className="tabular-nums">{new Date(post.created_at).toLocaleDateString("zh-CN")}</span>
-                    <span className="inline-flex items-center gap-1">
-                      <IconComment size={12} /> {post.comment_count}
-                    </span>
+                    {allowComments ? (
+                      <span className="inline-flex items-center gap-1">
+                        <IconComment size={12} /> {post.comment_count}
+                      </span>
+                    ) : null}
                     <span className="inline-flex items-center gap-1">
                       <IconEye size={12} /> {post.view_count}
                     </span>