feat(connector): Trustpay Refund & RSync flow

[Shubhodip900]

Description

Added Trustpay as connector with following flows:

• Refund
• RSync

Added payment_method field in .proto as trustpay need different header for different payment methods.

Motivation and Context

Additional Changes

• This PR modifies the API contract
• This PR modifies application configuration/environment variables

How did you test it?

Tested Using HS <> UCS tunnel

1. Refund Flow :-
   Request

{
  "payment_id": "pay_UW6JFQouNv1VvbBqWCsn",
  "amount": 6000,
  "reason": "Customer returned product",
  "refund_type": "instant",
  "metadata": {
    "udf1": "value1",
    "new_customer": "true",
    "login_date": "2019-09-10T10:11:12Z"
  }
}

Response

{
    "refund_id": "ref_bdgsXzb3jcOv42TXPjW7",
    "payment_id": "pay_UW6JFQouNv1VvbBqWCsn",
    "amount": 6000,
    "currency": "USD",
    "status": "succeeded",
    "reason": "Customer returned product",
    "metadata": {
        "udf1": "value1",
        "new_customer": "true",
        "login_date": "2019-09-10T10:11:12Z"
    },
    "error_message": null,
    "error_code": null,
    "unified_code": null,
    "unified_message": null,
    "created_at": "2025-12-05T11:57:17.177Z",
    "updated_at": "2025-12-05T11:57:17.721Z",
    "connector": "trustpay",
    "profile_id": "pro_OZ0QOMyj0DpOSwKmSs6p",
    "merchant_connector_id": "mca_8KKxRfJAhTIR7TBYqb9D",
    "split_refunds": null,
    "issuer_error_code": null,
    "issuer_error_message": null,
    "raw_connector_response": null
}

2. RSync Flow :-
   Response

{
    "refund_id": "ref_bdgsXzb3jcOv42TXPjW7",
    "payment_id": "pay_UW6JFQouNv1VvbBqWCsn",
    "amount": 6000,
    "currency": "USD",
    "status": "succeeded",
    "reason": "Customer returned product",
    "metadata": {
        "udf1": "value1",
        "new_customer": "true",
        "login_date": "2019-09-10T10:11:12Z"
    },
    "error_message": null,
    "error_code": null,
    "unified_code": null,
    "unified_message": null,
    "created_at": "2025-12-05T11:57:17.177Z",
    "updated_at": "2025-12-05T11:57:24.300Z",
    "connector": "trustpay",
    "profile_id": "pro_OZ0QOMyj0DpOSwKmSs6p",
    "merchant_connector_id": "mca_8KKxRfJAhTIR7TBYqb9D",
    "split_refunds": null,
    "issuer_error_code": null,
    "issuer_error_message": null,
    "raw_connector_response": null
}

Diff Check Result :-

1. Refund:-

2. RSync :-