fix: 空评论列表 500，并完善撤回审计与角色说明

空切片 JSON 统一为数组；撤回保留正文供站长阅读，成员侧居中提示与重新编辑；头像支持拖放；角色弹窗补全职责说明并汇入封禁。

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

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

@@ -28,7 +28,7 @@ export default function UserProfileContent({
     <div>
       {tab === "posts" ? (
         <div>
-          {profile.posts.length > 0 ? (
+          {Array.isArray(profile.posts) && profile.posts.length > 0 ? (
             <div className="panel overflow-hidden p-0">
               {profile.posts.map((post, i) => (
                 <Link
@@ -83,10 +83,10 @@ export default function UserProfileContent({
           <p className="meta mt-1.5 mb-4">网络异常，请稍后重试</p>
           <Link href={`/u/${userId}?tab=comments`} className="btn btn-line btn-sm">重新加载</Link>
         </div>
-      ) : commentData && commentData.comments.length > 0 ? (
+      ) : commentData && (commentData.comments?.length ?? 0) > 0 ? (
         <div>
           <div className="panel overflow-hidden p-0">
-            {commentData.comments.map((c, i) => (
+            {(commentData.comments ?? []).map((c, i) => (
               <Link
                 key={c.id}
                 href={`/post/${c.post_id}`}