feat(distribution): 通道费改主站承担，并按冷却期自动释放结算

利润不再扣支付通道费；站点可配置结算冷却期，到期自动入账，已释放后退款从收款站钱包回冲。同时修复当日自动批次无法追加、三方回冲打错钱包，以及测试库自增重置被 MySQL 统计缓存跳过的问题。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/internal/modules/distribution/pricing_test.go

@@ -37,14 +37,14 @@ func TestNormalizeSplitPercent(t *testing.T) {
 	}
 }
 
-func TestCalculateSettlementSplitsProfitAfterOwnerAndFee(t *testing.T) {
+func TestCalculateSettlementSplitsProfitWithoutPaymentFee(t *testing.T) {
 	rule := Rule{ServiceFeeValue: 25, ServiceFeeUnit: ServiceFeeUnitPercent, PaymentFeeBPS: 50}
 	got, err := CalculateSettlement(rule, SettlementInput{GrossPaidAmountCent: 10000, OwnerRentAmountCent: 6000})
 	if err != nil {
 		t.Fatal(err)
 	}
-	// 通道费 50，利润 10000-6000-50=3950，服务费 25%=988
-	if got.NetPaidAmountCent != 10000 || got.PaymentFeeCent != 50 || got.SplitBaseAmountCent != 3950 || got.ServiceFeeCent != 988 {
+	// 通道费 50 由主站承担（仅记录），利润 10000-6000=4000，服务费 25%=1000
+	if got.NetPaidAmountCent != 10000 || got.PaymentFeeCent != 50 || got.SplitBaseAmountCent != 4000 || got.ServiceFeeCent != 1000 {
 		t.Fatalf("unexpected settlement: %#v", got)
 	}
 }