feat: integrate unified payment and wallet refunds

backend/api/etc/heqi_dev.yaml

@@ -1,4 +1,4 @@
-Service: platform
+Service: heqi
 Port: 12426
 
 Databases:
@@ -22,3 +22,28 @@ Global:
   DeliveryArrivalRadiusMeters: 200
   UploadVideoMaxSize: 104857600
   FieldEncryptionKey: change-me-32-byte-development-key
+
+Payment:
+  ExpireMinutes: 30
+  RefundWindowDays: 3
+  InternalServiceToken: change-me-payment-worker-token
+  Alipay:
+    Enabled: false
+    Production: false
+    AppID: ""
+    PrivateKeyPath: ""
+    AppPublicCertPath: ""
+    AlipayPublicCertPath: ""
+    AlipayRootCertPath: ""
+    NotifyURL: "https://example.invalid/heqi/payment-return/v1/alipay/notify"
+    ReturnURL: "https://example.invalid/payment/result"
+  Wechat:
+    Enabled: false
+    MerchantID: ""
+    MerchantCertificateSerial: ""
+    MerchantPrivateKeyPath: ""
+    APIv3Key: ""
+    AppAppID: ""
+    OfficialAccountAppID: ""
+    MiniProgramAppID: ""
+    NotifyURL: "https://example.invalid/heqi/payment-return/v1/wechat/notify"