修复 Grok Realtime 关闭检查与 rollup 时区断言

golangci 要求检查 Realtime 上游 Close 返回值，并删除已无调用的 heavy-model 冷却函数。分组日汇总集成测试在 UTC 晚上跨上海零点时会把水位写成 UTC 日期，将会话时区钉到 Asia/Shanghai。

backend/internal/handler/grok_audio.go

@@ -121,7 +121,7 @@ func (h *OpenAIGatewayHandler) GrokRealtime(c *gin.Context) {
 		return
 	}
 	defer release()
-	defer upstream.Close()
+	defer func() { _ = upstream.Close() }()
 
 	conn, err := coderws.Accept(c.Writer, c.Request, &coderws.AcceptOptions{CompressionMode: coderws.CompressionContextTakeover})
 	if err != nil {

backend/internal/repository/group_usage_rollup_trigger_integration_test.go

@@ -151,6 +151,7 @@ func TestGroupUsageRollupTriggerSerializesInsertTransactionAcrossMidnight(t *tes
 
 	insertTx := beginGroupUsageRollupTriggerTestTx(t, ctx, schema)
 	defer func() { _ = insertTx.Rollback() }()
+	require.NoError(t, setGroupUsageRollupTriggerTimeZone(ctx, insertTx, "Asia/Shanghai"))
 	var insertBackendPID int
 	require.NoError(t, insertTx.QueryRowContext(ctx, "SELECT pg_backend_pid()").Scan(&insertBackendPID))
 
@@ -206,6 +207,7 @@ func TestGroupUsageRollupTriggerKeepsWatermarkForTodayInsert(t *testing.T) {
 
 	tx := beginGroupUsageRollupTriggerTestTx(t, ctx, schema)
 	defer func() { _ = tx.Rollback() }()
+	require.NoError(t, setGroupUsageRollupTriggerTimeZone(ctx, tx, "Asia/Shanghai"))
 	_, err := tx.ExecContext(ctx, `
 		INSERT INTO groups (id) VALUES (10);
 		INSERT INTO users (id) VALUES (1);
@@ -476,6 +478,11 @@ func setGroupUsageRollupTriggerSearchPath(ctx context.Context, tx *sql.Tx, quote
 	return err
 }
 
+func setGroupUsageRollupTriggerTimeZone(ctx context.Context, tx *sql.Tx, name string) error {
+	_, err := tx.ExecContext(ctx, "SET LOCAL TIME ZONE "+pq.QuoteLiteral(name))
+	return err
+}
+
 func waitForGroupUsageRollupStateLock(
 	ctx context.Context,
 	backendPID int,

backend/internal/service/grok_audio.go

@@ -133,7 +133,7 @@ func (s *OpenAIGatewayService) ProxyGrokRealtime(ctx context.Context, c *gin.Con
 	if err != nil {
 		return false, err
 	}
-	defer upstream.Close()
+	defer func() { _ = upstream.Close() }()
 	return s.ProxyGrokRealtimeConn(ctx, c, client, upstream)
 }
 

backend/internal/service/openai_gateway_grok.go

@@ -1809,11 +1809,6 @@ func grokRequestedModelFromCtx(ctx context.Context) string {
 	return strings.TrimSpace(model)
 }
 
-func isGrokHeavyTransientModel(requestedModel string) bool {
-	model := strings.ToLower(strings.TrimSpace(xai.ResolveGrokTextResponsesModelID(requestedModel)))
-	return strings.Contains(model, "multi-agent")
-}
-
 func persistGrokTransientModelCooldown(account *Account, decision GrokUpstreamFailureDecision) bool {
 	if account == nil {
 		return false