feat(auth): implement session-based token management with revocation support

Add Session model, SessionService, and SessionRepository to track user login
sessions and enable token revocation on auth-critical events.

- Introduce explicit TokenType (access/refresh) in JWT claims to prevent
  refresh token misuse via access token endpoints
- Add SessionID field to JWT claims, enabling stateless JWT validation
  against revoked sessions
- Replace legacy Auth middleware with RequireAuth/OptionalAuth pipeline
  that validates token type, account status, and session validity
- Implement session revocation on password change, reset, user ban/inactive,
  and explicit logout
- Add Principal cache with active invalidation for banned/role-changed users
- Fix IDOR vulnerability: GetMessagesByCursor now validates currentUserID
  is conversation participant via GetParticipantStrict
- Add group member visibility checks: announcements, group info, member list
  now require group membership
- Simplify Casbin policy: remove g grouping, use r.sub == p.sub matcher
  with globMatch; user_roles table is single source of truth for roles
- Add migration logic to clean legacy casbin g rules and migrate old p rules
  from path-style to admin/<domain> resource naming

internal/handler/group_handler.go

@@ -838,6 +838,8 @@ func (h *GroupHandler) HandleCreateAnnouncement(c *gin.Context) {
 
 // HandleGetAnnouncements 获取群公告列表
 // GET /api/v1/groups/:id/announcements
+//
+// 可见性策略：仅群成员可见。非成员返回 403 NOT_GROUP_MEMBER。
 func (h *GroupHandler) HandleGetAnnouncements(c *gin.Context) {
 	userID := parseUserID(c)
 	if userID == "" {
@@ -851,6 +853,12 @@ func (h *GroupHandler) HandleGetAnnouncements(c *gin.Context) {
 		return
 	}
 
+	// 成员校验：公告仅群成员可见。
+	if !h.groupService.IsGroupMember(userID, groupID) {
+		response.Forbidden(c, "不是群成员")
+		return
+	}
+
 	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
 	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
 
@@ -1387,7 +1395,9 @@ func (h *GroupHandler) GetMembersByCursor(c *gin.Context) {
 }
 
 // GetAnnouncementsByCursor 游标分页获取群公告列表
-// GET /api/groups/:id/announcements/cursor
+// GET /api/v1/groups/:id/announcements/cursor
+//
+// 可见性策略：仅群成员可见。非成员返回 403 NOT_GROUP_MEMBER。
 func (h *GroupHandler) GetAnnouncementsByCursor(c *gin.Context) {
 	userID := parseUserID(c)
 	if userID == "" {
@@ -1401,6 +1411,12 @@ func (h *GroupHandler) GetAnnouncementsByCursor(c *gin.Context) {
 		return
 	}
 
+	// 成员校验
+	if !h.groupService.IsGroupMember(userID, groupID) {
+		response.Forbidden(c, "不是群成员")
+		return
+	}
+
 	// 解析游标分页请求
 	req := h.parseCursorRequest(c)
 
@@ -1937,6 +1953,8 @@ func (h *GroupHandler) HandleRespondInvite(c *gin.Context) {
 
 // HandleGetGroupInfo 获取群信息
 // GET /api/v1/groups/:id
+//
+// 可见性策略：成员返回完整详情；非成员仅返回公开字段（name/avatar/description/member_count）。
 func (h *GroupHandler) HandleGetGroupInfo(c *gin.Context) {
 	userID := parseUserID(c)
 	if userID == "" {
@@ -1967,11 +1985,26 @@ func (h *GroupHandler) HandleGetGroupInfo(c *gin.Context) {
 	resp := dto.GroupToResponse(group)
 	resp.MemberCount = memberCount
 
+	// 非成员仅返回公开字段：与成员分支同构（仍是 GroupResponse），但清空敏感字段。
+	// 与成员分支共用 GroupResponse 结构，依赖完整字段的客户端解析不会因字段缺失出错。
+	if !h.groupService.IsGroupMember(userID, groupID) {
+		resp.OwnerID = ""
+		resp.MaxMembers = 0
+		resp.JoinType = 0
+		resp.MuteAll = false
+		resp.IsMember = false
+		response.Success(c, resp)
+		return
+	}
+
+	resp.IsMember = true
 	response.Success(c, resp)
 }
 
 // HandleGetGroupMemberList 获取群成员列表
 // GET /api/v1/groups/:id/members
+//
+// 可见性策略：仅群成员可见。非成员返回 403 NOT_GROUP_MEMBER。
 func (h *GroupHandler) HandleGetGroupMemberList(c *gin.Context) {
 	userID := parseUserID(c)
 	if userID == "" {
@@ -1988,8 +2021,13 @@ func (h *GroupHandler) HandleGetGroupMemberList(c *gin.Context) {
 	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
 	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "50"))
 
-	members, total, err := h.groupService.GetMembers(groupID, page, pageSize)
+	// 成员校验在 service 层完成。
+	members, total, err := h.groupService.GetMembersForUser(userID, groupID, page, pageSize)
 	if err != nil {
+		if errors.Is(err, service.ErrNotGroupMember) {
+			response.Forbidden(c, "不是群成员")
+			return
+		}
 		if errors.Is(err, service.ErrGroupNotFound) {
 			response.NotFound(c, "群组不存在")
 			return