feat: 帖子分级置顶（板块/全站）与板块管理员置顶权限、消息管理权限调整

backend/handler/chat.go

@@ -69,7 +69,7 @@ func (h *Handlers) chatOversee(userID uint) bool {
 	if err != nil || actor == nil {
 		return false
 	}
-	return service.CanOverseeChat(actor.Role)
+	return actor.CanOverseeChat()
 }
 
 // RequireMessagesOpen 前台群聊/私聊闸门；关闭后一律 403。管理端 /api/admin/chat 不受影响。
@@ -673,7 +673,7 @@ func (h *Handlers) AdminChatMessages(c *gin.Context) {
 		"messages":      msgs,
 		"total":         total,
 		"page":          page,
-		"can_oversee":   service.CanOverseeChat(actor.Role),
+		"can_oversee":   actor.CanOverseeChat(),
 		"can_recall":    true,
 		"site_messages": actor.HasSiteMessagePerm(),
 	})
@@ -697,7 +697,7 @@ func (h *Handlers) AdminRecallChatMessage(c *gin.Context) {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "消息 ID 无效"})
 		return
 	}
-	oversee := service.CanOverseeChat(actor.Role)
+	oversee := actor.CanOverseeChat()
 	msg, newly, err := h.Chat.RecallMessage(claims.ID, uint(roomID), uint(mid), oversee)
 	if err != nil {
 		c.JSON(chatErrToStatus(err), gin.H{"error": err.Error()})