add tax

app/main/api/internal/config/config.go

@@ -25,6 +25,7 @@ type Config struct {
 	Query          QueryConfig
 	AdminConfig    AdminConfig
 	AdminPromotion AdminPromotion
+	TaxConfig      TaxConfig
 }
 
 // JwtAuth 用于 JWT 鉴权配置
@@ -124,3 +125,7 @@ type AdminConfig struct {
 type AdminPromotion struct {
 	URLDomain string
 }
+type TaxConfig struct {
+	TaxRate            float64
+	TaxExemptionAmount float64
+}