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>

backend/handler/comment.go

@@ -36,6 +36,21 @@ func (h *Handlers) PostComments(c *gin.Context) {
 		c.JSON(http.StatusNotFound, gin.H{"error": "帖子不存在"})
 		return
 	}
+
+	if allow, err := h.Setting.AllowComments(); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "评论暂时不可用"})
+		return
+	} else if !allow {
+		c.JSON(http.StatusOK, gin.H{
+			"comments":       []any{},
+			"total":          0,
+			"total_comments": 0,
+			"page":           page,
+			"size":           size,
+		})
+		return
+	}
+
 	boardID, _ := h.Post.GetBoardID(uint(id))
 
 	comments, floors, totalComments, err := h.Comment.ListFloorPaged(uint(id), boardID, viewerID, actor, page, size)
@@ -70,7 +85,7 @@ func (h *Handlers) CreateComment(c *gin.Context) {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "评论暂时不可用"})
 		return
 	} else if !allow {
-		c.JSON(http.StatusForbidden, gin.H{"error": "站点已关闭评论"})
+		c.JSON(http.StatusForbidden, gin.H{"error": "本站不支持评论"})
 		return
 	}
 	var req CreateCommentRequest