fix: harden group lifecycle and registration writes

server/im_http_test.go

@@ -5843,11 +5843,11 @@ func TestNormalizeIMUserVisibleTopicSelf(t *testing.T) {
 	}
 }
 
-func TestMergeGroupSettingsPayloadPreservesTopicVersion(t *testing.T) {
+func TestMergeGroupSettingsPayloadUsesSettingsVersion(t *testing.T) {
 	payload := map[string]any{"version": 7}
 	mergeGroupSettingsPayload(payload, &types.GroupSettings{Version: 2})
-	if payload["version"] != 7 {
-		t.Fatalf("topic version was overwritten: %#v", payload)
+	if payload["version"] != 2 {
+		t.Fatalf("settings version was not used: %#v", payload)
 	}
 }