feat: 实时消息与管理端运营能力

新增群聊/私信与公共 WebSocket 总线，站长用户内容档案，并将通知与待审角标改为推送驱动；同步精简管理仪表盘并修复主题换肤 DOM 冲突。

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

backend/handler/auth.go

@@ -117,6 +117,7 @@ func (h *Handlers) Register(c *gin.Context) {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
+	_ = h.Chat.EnsureDefaultMembership(user.ID)
 	// 自动登录：走与 Login 相同的 token 签发链路
 	accessToken, refreshToken, loginUser, err := h.Auth.Login(req.Username, req.Password)
 	if err != nil {
@@ -263,7 +264,7 @@ func meUserBody(user *model.User, boardIDs []uint) gin.H {
 func (h *Handlers) Me(c *gin.Context) {
 	claims := middleware.CurrentUser(c)
 	if claims == nil {
-		resp := gin.H{"user": nil, "unread_count": 0}
+		resp := gin.H{"user": nil, "unread_count": 0, "chat_unread_count": 0}
 		// OptionalAuth 识别到封禁：HTTP 仍为 200（/me 不阻断页面），
 		// 但带 banned/code，客户端静默校正时据此强制下线并弹告知
 		if c.GetBool(middleware.AccountBannedKey) {
@@ -275,17 +276,22 @@ func (h *Handlers) Me(c *gin.Context) {
 	}
 	user, err := h.Auth.GetUserByID(claims.ID)
 	if err != nil {
-		c.JSON(http.StatusOK, gin.H{"user": nil, "unread_count": 0})
+		c.JSON(http.StatusOK, gin.H{"user": nil, "unread_count": 0, "chat_unread_count": 0})
 		return
 	}
 	var unread int64
 	if n, err := h.Notification.UnreadCount(claims.ID); err == nil {
 		unread = n
 	}
+	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 {
 		boardIDs, _ = h.Auth.GetUserBoardIDs(claims.ID)
 	}
-	c.JSON(http.StatusOK, gin.H{"user": meUserBody(user, boardIDs), "unread_count": unread})
+	c.JSON(http.StatusOK, gin.H{
+		"user":              meUserBody(user, boardIDs),
+		"unread_count":      unread,
+		"chat_unread_count": chatUnread,
+	})
 }