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/message_handler.go

@@ -1108,10 +1108,10 @@ func (h *MessageHandler) GetMessagesByCursor(c *gin.Context) {
 	// 解析游标分页参数
 	pageReq := parseCursorPageRequest(c)
 
-	// 调用服务层
-	result, err := h.messageService.GetMessagesByCursor(c.Request.Context(), conversationID, pageReq)
+	// 调用服务层（内部会校验 currentUserID 是否是会话参与者，否则拒绝）
+	result, err := h.messageService.GetMessagesByCursor(c.Request.Context(), conversationID, userID, pageReq)
 	if err != nil {
-		response.InternalServerError(c, "failed to get messages")
+		response.HandleError(c, err, "failed to get messages")
 		return
 	}