feat(群组): 添加群组解散状态支持与过滤逻辑

新增群组解散状态常量，在群组列表和详情接口中增加解散群组的过滤和报错处理，避免返回已解散的群组数据

server/im_http.go

@@ -55,6 +55,7 @@ const (
 	imReasonFileUnavailable     = "FILE_UNAVAILABLE"
 	imReasonRateLimited         = "RATE_LIMITED"
 	imReasonResourceNotFound    = "RESOURCE_NOT_FOUND"
+	imReasonGroupDissolved      = "GROUP_DISSOLVED"
 	imReasonValidationFailed    = "VALIDATION_FAILED"
 )
 
@@ -4774,7 +4775,11 @@ func serveIMGroupList(wrt http.ResponseWriter, req *http.Request) {
 			continue
 		}
 		item := groupListItemPayload(sub)
-		if settings, err := store.GroupBusiness.GetSettings(principal.TenantID, sub.Topic); err == nil {
+		if settings, err := store.GroupBusiness.GetSettings(principal.TenantID, sub.Topic); err == nil && settings != nil {
+			if settings.GroupStatus == types.GroupStatusDissolved {
+				// Defensive check: hide dissolved groups even if their subscription cleanup lagged.
+				continue
+			}
 			item = mergeGroupListSettingsPayload(item, settings)
 		}
 		if category != "" && groupCategory(groupMemberRole(sub.ModeGiven&sub.ModeWant)) != category {
@@ -5083,6 +5088,10 @@ func serveIMGroupDetail(wrt http.ResponseWriter, req *http.Request, topic string
 		}
 		payload := groupDetailPayload(group, selfSub)
 		if settings, err := store.GroupBusiness.GetSettings(principal.TenantID, topic); err == nil {
+			if settings != nil && settings.GroupStatus == types.GroupStatusDissolved {
+				writeIMError(wrt, req, http.StatusGone, 30004, imReasonGroupDissolved, "group dissolved", map[string]any{"topic": topic})
+				return
+			}
 			payload = mergeGroupSettingsPayload(payload, settings)
 		}
 		writeIMSuccess(wrt, req, payload)

server/store/types/groups.go

@@ -3,7 +3,8 @@ package types
 import "time"
 
 const (
-	GroupStatusActive = "active"
+	GroupStatusActive    = "active"
+	GroupStatusDissolved = "dissolved"
 
 	GroupMemberRoleOwner  = "owner"
 	GroupMemberRoleAdmin  = "admin"