feat: 后台增加开放消息开关

关闭后前台隐藏私聊/群聊入口并由后端拦截；同步去掉公告页重复计数胶囊。

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

backend/handler/auth.go

@@ -279,7 +279,12 @@ func (h *Handlers) Me(c *gin.Context) {
 	if n, err := h.Notification.UnreadCount(claims.ID); err == nil {
 		unread = n
 	}
-	chatUnread := h.Chat.TotalUnread(claims.ID)
+	chatUnread := int64(0)
+	if h.Setting != nil && h.Chat != nil {
+		if allow, err := h.Setting.AllowMessages(); err == nil && allow {
+			chatUnread = h.Chat.TotalUnread(claims.ID)
+		}
+	}
 	// 板块管理员带出授权板块，供前端菜单/按钮按板块范围渲染
 	var boardIDs []uint
 	if user.Role == model.RoleBoardAdmin {

backend/handler/chat.go

@@ -47,15 +47,33 @@ func (h *Handlers) chatOversee(userID uint) bool {
 	return service.CanOverseeChat(actor.Role)
 }
 
+// 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。
+func (h *Handlers) RequireMessagesOpen(c *gin.Context) {
+	if h.Setting == nil {
+		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"error": "消息暂时不可用"})
+		return
+	}
+	allow, err := h.Setting.AllowMessages()
+	if err != nil {
+		c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{"error": "消息暂时不可用"})
+		return
+	}
+	if !allow {
+		c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"error": "本站不支持消息"})
+		return
+	}
+	c.Next()
+}
+
 // CreateChatRoom 建群（可公开/私密，私密可带初始成员）
 func (h *Handlers) CreateChatRoom(c *gin.Context) {
 	claims := middleware.CurrentUser(c)
 	var req struct {
-		Name             string   `json:"name"`
-		Description      string   `json:"description"`
-		IsPrivate        bool     `json:"is_private"`
-		MemberIDs        []uint   `json:"member_ids"`
-		MemberUsernames  []string `json:"member_usernames"`
+		Name            string   `json:"name"`
+		Description     string   `json:"description"`
+		IsPrivate       bool     `json:"is_private"`
+		MemberIDs       []uint   `json:"member_ids"`
+		MemberUsernames []string `json:"member_usernames"`
 	}
 	if err := c.ShouldBindJSON(&req); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "请求参数无效"})

backend/handler/setting.go

@@ -27,6 +27,7 @@ type updateSettingsRequest struct {
 	SiteDescription      *string `json:"site_description"`
 	AllowRegister        *bool   `json:"allow_register"`
 	AllowComments        *bool   `json:"allow_comments"`
+	AllowMessages        *bool   `json:"allow_messages"`
 	PostCooldownHours    *int    `json:"post_cooldown_hours"`
 	CodeBlockAutoFold    *bool   `json:"code_block_auto_fold"`
 	CodeBlockFoldLines   *int    `json:"code_block_fold_lines"`
@@ -45,6 +46,7 @@ func settingsPayload(saved service.PublicSiteSettings) gin.H {
 		"site_description":       saved.SiteDescription,
 		"allow_register":         saved.AllowRegister,
 		"allow_comments":         saved.AllowComments,
+		"allow_messages":         saved.AllowMessages,
 		"post_cooldown_hours":    saved.PostCooldownHours,
 		"code_block_auto_fold":   saved.CodeBlockAutoFold,
 		"code_block_fold_lines":  saved.CodeBlockFoldLines,
@@ -65,6 +67,7 @@ func (h *Handlers) UpdateSettings(c *gin.Context) {
 	}
 	if req.Accent == nil && req.TrustReviewedPublish == nil && req.SiteName == nil &&
 		req.SiteDescription == nil && req.AllowRegister == nil && req.AllowComments == nil &&
+		req.AllowMessages == nil &&
 		req.PostCooldownHours == nil && req.CodeBlockAutoFold == nil && req.CodeBlockFoldLines == nil &&
 		req.UIAnimations == nil && req.AnimCodeFold == nil && req.AnimSmoothScroll == nil &&
 		req.AnimChrome == nil && req.PostLinkNewTab == nil {
@@ -120,6 +123,12 @@ func (h *Handlers) UpdateSettings(c *gin.Context) {
 			return
 		}
 	}
+	if req.AllowMessages != nil {
+		if err := h.Setting.SetAllowMessages(*req.AllowMessages); err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "保存站点设置失败"})
+			return
+		}
+	}
 	if req.PostCooldownHours != nil {
 		if err := h.Setting.SetPostCooldownHours(*req.PostCooldownHours); err != nil {
 			if errors.Is(err, service.ErrInvalidSiteSetting) {