fix(gateway): adminListChannels 按平台聚合——bare+kook多个adapter不再拆成多行导致重复账号

- 根因: caps循环把 kook(bare)+kook:fc2048(多账号) 分别append, 每行Accounts都是完整platform账号集→前端显示两个kook且fc2048重复(主人'只点一次创建出两个kook')
- 修: 按platform聚合(hasChannelSummary检查), 同platform只一行(Name=platform), Accounts为整个platform账号集; 保留agent-121删除同步(平台有账号才显示)
- 测试断言: kook:3fc8/conf0 → kook(聚合行) 更新
- 全仓 go build/vet/test绿; 前端无涉

internal/services/gateway/admin_write_channel_config_test.go

@@ -202,10 +202,10 @@ func TestAdminDeleteChannelAccountRemovesFromList(t *testing.T) {
 	_, ts, jwt := buildEnv(t, cfgDefault(), Deps{Registry: caps, Channels: store})
 	tok := signAny(t, jwt, "acct", auth.RoleOwner)
 
-	// Before the delete the account shows up.
+	// Before the delete the account shows up (aggregated into a single "kook" row).
 	items, _ := adminChannelsList(t, ts, tok)
-	if len(items) != 1 || items[0].Name != "kook:3fc8" {
-		t.Fatalf("before delete items = %+v, want [kook:3fc8]", items)
+	if len(items) != 1 || items[0].Name != "kook" || len(items[0].Accounts) != 1 || items[0].Accounts[0].ID != "3fc8" {
+		t.Fatalf("before delete items = %+v, want one kook row with account 3fc8", items)
 	}
 
 	resp, body := doReq(t, http.MethodDelete, ts.URL+"/api/v1/admin/channels/kook/config?id=3fc8", nil, tok)
@@ -252,8 +252,8 @@ func TestAdminDeleteChannelAccountKeepsSibling(t *testing.T) {
 	}
 
 	items, _ := adminChannelsList(t, ts, tok)
-	if len(items) != 1 || items[0].Name != "kook:conf1" {
-		t.Fatalf("items = %+v, want only kook:conf1 (deleted 3fc8 must vanish)", items)
+	if len(items) != 1 || items[0].Name != "kook" {
+		t.Fatalf("items = %+v, want one kook row (deleted 3fc8 must vanish)", items)
 	}
 	if len(items[0].Accounts) != 1 || items[0].Accounts[0].ID != "conf1" {
 		t.Fatalf("accounts = %+v, want only conf1", items[0].Accounts)