feat(moderation): 帖评删除占位感知与硬删清场

管理删帖须填类型与理由并展示专用页；评论软删占位、版主可硬删不占楼。

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

frontend/app/post/[id]/page.tsx

@@ -18,12 +18,13 @@ import {
   fetchComments,
   fetchPosts,
   fetchUserProfile,
+  postDeleteTypeLabel,
   type UserProfile,
   type PostListItem,
   type Board,
 } from "@/lib/api";
 import { authCookieHeader } from "@/lib/cookies";
-import { getMeCached } from "@/lib/serverData";
+import { getMeCached, getPublicSettingsCached } from "@/lib/serverData";
 import CommentSection from "@/components/CommentSection";
 import PostActions from "@/components/PostActions";
 import LikeButton from "@/components/LikeButton";
@@ -50,9 +51,16 @@ export async function generateMetadata({ params }: PageProps): Promise<Metadata>
   try {
     // 带登录态：作者/管理团队看待审帖时标签标题也应是真实标题而非"帖子不存在"
     const { post } = await fetchPostDetail(id, authCookieHeader(await cookies()));
+    if (post.tombstone) {
+      return {
+        title: post.title || "帖子已删除",
+        description: "该帖子已被删除",
+        robots: { index: false, follow: false },
+      };
+    }
     const desc = post.content_locked
       ? post.access_hint || "部分内容需满足条件后可见"
-      : post.content.slice(0, 160);
+      : (post.content || "").slice(0, 160);
     return {
       title: post.title,
       description: desc,
@@ -383,10 +391,63 @@ export default async function PostDetailPage({ params, searchParams }: PageProps
     notFound();
   }
 
-  // 评论 / 当前用户 / 作者资料 / 同板块热议并行拉取；侧栏数据失败一律静默降级，不阻塞正文
-  const [commentsData, me, profile, relatedData] = await Promise.all([
+  // 软删专用页：列表已不可见，原链接展示删除说明
+  if (post.tombstone) {
+    const typeLabel = postDeleteTypeLabel(post.delete_type);
+    return (
+      <div className="max-w-lg mx-auto py-16 px-4 text-center">
+        <p
+          className="inline-flex items-center rounded-full px-3 py-1 text-[12px] font-semibold mb-4"
+          style={{ background: "var(--danger-soft)", color: "var(--danger)" }}
+        >
+          帖子已删除
+        </p>
+        <h1 className="text-[20px] sm:text-[22px] font-extrabold mb-3" style={{ color: "var(--ink)" }}>
+          {post.title || "（无标题）"}
+        </h1>
+        {post.staff_deleted ? (
+          <div
+            className="panel text-left p-5 sm:p-6 mt-2"
+            style={{ borderColor: "var(--danger-soft)" }}
+          >
+            <p className="text-[14px] font-medium mb-3" style={{ color: "var(--ink)" }}>
+              此帖已被管理员删除
+            </p>
+            {typeLabel && (
+              <p className="text-[13px] mb-2" style={{ color: "var(--ink-2)" }}>
+                <span style={{ color: "var(--ink-3)" }}>类型：</span>
+                {typeLabel}
+              </p>
+            )}
+            {post.delete_reason && (
+              <p className="text-[13px] leading-relaxed" style={{ color: "var(--ink-2)" }}>
+                <span style={{ color: "var(--ink-3)" }}>理由：</span>
+                {post.delete_reason}
+              </p>
+            )}
+          </div>
+        ) : (
+          <p className="meta text-[14px] mt-2">作者已删除此帖</p>
+        )}
+        <div className="mt-8 flex items-center justify-center gap-3">
+          <Link href="/" className="btn btn-line btn-sm">
+            返回首页
+          </Link>
+          {post.board?.id ? (
+            <Link href={`/?board=${post.board_id}`} className="btn btn-primary btn-sm">
+              浏览板块
+            </Link>
+          ) : null}
+        </div>
+      </div>
+    );
+  }
+
+  // 评论 / 当前用户 / 站点设置 / 作者资料 / 同板块热议并行拉取；侧栏数据失败一律静默降级，不阻塞正文
+  const [commentsData, me, siteSettings, profile, relatedData] = await Promise.all([
     fetchComments(id, commentPage, cookie),
     getMeCached(cookie || undefined),
+    getPublicSettingsCached(),
     fetchUserProfile(String(post.user.id), 1, cookie).catch(() => null),
     fetchPosts(1, 8, post.board_id, "recommended", "", false, cookie).catch(() => null),
   ]);
@@ -554,6 +615,7 @@ export default async function PostDetailPage({ params, searchParams }: PageProps
                     pinned={post.pinned}
                     recommended={post.recommended}
                     status={post.status}
+                    title={post.title}
                   />
                 </div>
 
@@ -659,6 +721,7 @@ export default async function PostDetailPage({ params, searchParams }: PageProps
                 page={commentsData.page}
                 size={commentsData.size}
                 user={me.user}
+                allowComments={siteSettings.allow_comments}
                 acceptMode={acceptMode}
                 acceptedCommentId={
                   post.question?.accepted_comment_id ||