fix: 评论系统全量检查修复（7 项 Gap 全部修复）

- Delete 权限：新增 requesterID/isAdmin 参数，Service 层鉴权（仅本人/管理员可删）
- 通知内容：改用 GetUsernameByID 显示真实用户名，非数字 UID
- SearchUsers：Repository 返回 exp，Service 调用 GetLevelByExp 计算等级
- 通知高亮：Notification 新增 CommentID 字段，消息链接支持 #comment-{id}
- 已删除提示：前端 hash 检测 + 3 秒超时 Toast "该评论已不存在"
- Admin CSS：移除不存在的 comments.css 引用
- 错误哨兵：改用 common.ErrCommentNotFound/ErrCommentEmpty/PermissionDenied

templates/MetaLab-2026/html/messages/index.html

@@ -42,7 +42,11 @@
             {{if or (eq $m.NotifyType "post_approved") (eq $m.NotifyType "post_rejected")}}
                 {{$link = printf "/posts/%d" (derefUint $m.RelatedID)}}
             {{else if or (eq $m.NotifyType "comment") (eq $m.NotifyType "comment_reply")}}
-                {{$link = printf "/posts/%d#comments" (derefUint $m.RelatedID)}}
+                {{if $m.CommentID}}
+                    {{$link = printf "/posts/%d#comment-%d" (derefUint $m.RelatedID) (derefUint $m.CommentID)}}
+                {{else}}
+                    {{$link = printf "/posts/%d#comments" (derefUint $m.RelatedID)}}
+                {{end}}
             {{else if or (eq $m.NotifyType "audit_approved") (eq $m.NotifyType "audit_rejected")}}
                 {{$link = "/settings"}}
             {{end}}

templates/MetaLab-2026/html/posts/show.html

@@ -703,8 +703,55 @@
         });
     }
 
-    // ====== Hash 定位：从消息通知跳转时滚动到评论区 ======
-    if (window.location.hash === '#comments') {
+    // ====== 评论高亮 + 已删除评论Toast ======
+    function showToast(msg) {
+        var toast = document.createElement('div');
+        toast.className = 'toast';
+        toast.textContent = msg;
+        toast.style.cssText = 'position:fixed;top:20px;left:50%;transform:translateX(-50%);background:rgba(0,0,0,0.85);color:#fff;padding:10px 24px;border-radius:6px;font-size:14px;z-index:9999;animation:fadeIn 0.3s ease';
+        document.body.appendChild(toast);
+        setTimeout(function() {
+            toast.style.opacity = '0';
+            toast.style.transition = 'opacity 0.3s';
+            setTimeout(function() { toast.remove(); }, 300);
+        }, 2500);
+    }
+
+    function highlightComment(commentId) {
+        var card = commentsList.querySelector('.comment-card[data-id="' + commentId + '"]') ||
+                   commentsList.querySelector('.comment-reply-card[data-id="' + commentId + '"]');
+        if (card) {
+            // 置顶：移动卡片到列表顶部
+            commentsList.insertBefore(card, commentsList.firstChild);
+            card.scrollIntoView({ behavior: 'smooth', block: 'start' });
+            card.style.background = '#fff8e1';
+            card.style.transition = 'background 1.5s';
+            setTimeout(function() { card.style.background = ''; }, 2000);
+            return true;
+        }
+        return false;
+    }
+
+    // 解析 hash（支持 #comment-{id}、#comments 以及回退）
+    var hash = window.location.hash;
+    var commentMatch = hash.match(/^#comment-(\d+)$/);
+    if (commentMatch) {
+        var targetCommentId = commentMatch[1];
+        // 等待评论加载完成后查找
+        var checkInterval = setInterval(function() {
+            if (highlightComment(targetCommentId)) {
+                clearInterval(checkInterval);
+            }
+        }, 300);
+        // 3秒后超时（评论可能已被删除）
+        setTimeout(function() {
+            clearInterval(checkInterval);
+            if (!commentsList.querySelector('.comment-card[data-id="' + targetCommentId + '"]') &&
+                !commentsList.querySelector('.comment-reply-card[data-id="' + targetCommentId + '"]')) {
+                showToast('该评论已不存在');
+            }
+        }, 3000);
+    } else if (hash === '#comments') {
         setTimeout(function() {
             var section = document.getElementById('comments');
             if (section) {