fix: 包年改为 Waffo 一次性商品并切 CNY

包年 SKU 换为 PROD_1BIezCi932IbgCzRIV8hcJ，checkout type 统一 onetime。

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

backend/internal/service/payment/waffo.go

@@ -31,7 +31,7 @@ func LoadWaffoConfig() WaffoConfig {
 	}
 	currency := strings.TrimSpace(os.Getenv("WAFFO_CURRENCY"))
 	if currency == "" {
-		currency = "USD"
+		currency = "CNY"
 	}
 	defaultProduct := strings.TrimSpace(os.Getenv("WAFFO_PRODUCT_ID"))
 	yearly := strings.TrimSpace(os.Getenv("WAFFO_PRODUCT_ID_YEARLY"))
@@ -104,12 +104,9 @@ func productIDForPlan(cfg WaffoConfig, planType string) string {
 }
 
 func checkoutTypeForPlan(planType string) string {
-	switch strings.TrimSpace(planType) {
-	case "yearly", "monthly":
-		return "subscription"
-	default:
-		return "onetime"
-	}
+	// OpsXShell 包年 / 永久均为 Waffo onetime 商品（包年不再走 subscription）。 // Logan.Li
+	_ = planType
+	return "onetime"
 }
 
 func resolveBaseCheckoutURL(cfg WaffoConfig, planType string) (*url.URL, error) {