Issue:
Bug: Fix payment redirects for v2



Fix payment redirects for v2

Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
This PR fixes payment redirects in v2. This was due to the field merchant_connector_details set as todo!()

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that will have little conversation).
-->


## How did you test it?
<!--
Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
-->

- Make 3DS payment
```
curl --location 'http://localhost:8080/v2/payments' \
--header 'Content-Type: application/json' \
--header 'x-profile-id: pro_295oknnkIU8LhiO6RTCy' \
--header 'Authorization: api-key=dev_8OKnwsVtu4ZIxxgqDfVQwnQrUfdORX3Ivo9i8Yxp0rB3mEZxiv9UZchQimjPgNnx' \
--data-raw '{
  "amount_details": {
    "currency": "USD",
    "order_amount": 6540
  },
  "authentication_type": "three_ds",
  "payment_method_data": {
    "card": {
      "card_cvc": "123",
      "card_exp_month": "10",
      "card_exp_year": "25",
      "card_holder_name": "joseph Doe",
      "card_number": "4242424242424242"
    }
  },
  "payment_method_subtype": "credit",
  "payment_method_type": "card"
}'
```
Response
```
{
    "id": "12345_pay_01978cfda5fa7c12b1ba298cca0470c2",
    "status": "requires_customer_action",
    "amount": {
        "order_amount": 6540,
        "currency": "USD",
        "shipping_cost": null,
        "order_tax_amount": null,
        "external_tax_calculation": "skip",
        "surcharge_calculation": "skip",
        "surcharge_amount": null,
        "tax_on_surcharge": null,
        "net_amount": 6540,
        "amount_to_capture": null,
        "amount_capturable": 0,
        "amount_captured": null
    },
    "customer_id": null,
    "connector": "stripe",
    "created": "2025-06-20T10:58:42.813Z",
    "payment_method_data": {
        "billing": null
    },
    "payment_method_type": "card",
    "payment_method_subtype": "credit",
    "connector_transaction_id": "pi_3Rc2edD5R7gDAGff01vwkClL",
    "connector_reference_id": null,
    "merchant_connector_id": "mca_0GI0dABwex0qdnwlUelt",
    "browser_info": null,
    "error": null,
    "shipping": null,
    "billing": null,
    "attempts": null,
    "connector_token_details": {
        "token": "pm_1Rc2edD5R7gDAGffEOosatGV",
        "connector_token_request_reference_id": "eDuVwDClp0zQPbbkLZ"
    },
    "payment_method_id": null,
    "next_action": {
        "type": "redirect_to_url",
        "redirect_to_url": "http://localhost:8080/v2/payments/12345_pay_01978cfda5fa7c12b1ba298cca0470c2/start-redirection?publishable_key=pk_dev_4499ca4660714d6b83b379218164187a&profile_id=pro_295oknnkIU8LhiO6RTCy"
    },
    "return_url": "https://google.com/success",
    "authentication_type": "three_ds",
    "authentication_type_applied": "three_ds",
    "is_iframe_redirection_enabled": null,
    "merchant_reference_id": null
}
```
Redirect to URL

- Payments Sync
```
curl --location 'http://localhost:8080/v2/payments/12345_pay_01978cfda5fa7c12b1ba298cca0470c2?force_sync=true' \
--header 'x-profile-id: pro_295oknnkIU8LhiO6RTCy' \
--header 'Authorization: api-key=dev_8OKnwsVtu4ZIxxgqDfVQwnQrUfdORX3Ivo9i8Yxp0rB3mEZxiv9UZchQimjPgNnx' \
--data ''
```
Response
```
{
    "id": "12345_pay_01978cfda5fa7c12b1ba298cca0470c2",
    "status": "succeeded",
    "amount": {
        "order_amount": 6540,
        "currency": "USD",
        "shipping_cost": null,
        "order_tax_amount": null,
        "external_tax_calculation": "skip",
        "surcharge_calculation": "skip",
        "surcharge_amount": null,
        "tax_on_surcharge": null,
        "net_amount": 6540,
        "amount_to_capture": null,
        "amount_capturable": 0,
        "amount_captured": 6540
    },
    "customer_id": null,
    "connector": "stripe",
    "created": "2025-06-20T10:58:42.813Z",
    "payment_method_data": {
        "billing": null
    },
    "payment_method_type": "card",
    "payment_method_subtype": "credit",
    "connector_transaction_id": "pi_3Rc2edD5R7gDAGff01vwkClL",
    "connector_reference_id": null,
    "merchant_connector_id": "mca_0GI0dABwex0qdnwlUelt",
    "browser_info": null,
    "error": null,
    "shipping": null,
    "billing": null,
    "attempts": null,
    "connector_token_details": {
        "token": "pm_1Rc2edD5R7gDAGffEOosatGV",
        "connector_token_request_reference_id": "eDuVwDClp0zQPbbkLZ"
    },
    "payment_method_id": null,
    "next_action": null,
    "return_url": "https://google.com/success",
    "authentication_type": "three_ds",
    "authentication_type_applied": null,
    "is_iframe_redirection_enabled": null,
    "merchant_reference_id": null
}
```


## Checklist
<!-- Put an `x` in the boxes that apply -->

- [ ] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible


Testing:


- Make 3DS payment
```
curl --location 'http://localhost:8080/v2/payments' \
--header 'Content-Type: application/json' \
--header 'x-profile-id: pro_295oknnkIU8LhiO6RTCy' \
--header 'Authorization: api-key=dev_8OKnwsVtu4ZIxxgqDfVQwnQrUfdORX3Ivo9i8Yxp0rB3mEZxiv9UZchQimjPgNnx' \
--data-raw '{
  "amount_details": {
    "currency": "USD",
    "order_amount": 6540
  },
  "authentication_type": "three_ds",
  "payment_method_data": {
    "card": {
      "card_cvc": "123",
      "card_exp_month": "10",
      "card_exp_year": "25",
      "card_holder_name": "joseph Doe",
      "card_number": "4242424242424242"
    }
  },
  "payment_method_subtype": "credit",
  "payment_method_type": "card"
}'
```
Response
```
{
    "id": "12345_pay_01978cfda5fa7c12b1ba298cca0470c2",
    "status": "requires_customer_action",
    "amount": {
        "order_amount": 6540,
        "currency": "USD",
        "shipping_cost": null,
        "order_tax_amount": null,
        "external_tax_calculation": "skip",
        "surcharge_calculation": "skip",
        "surcharge_amount": null,
        "tax_on_surcharge": null,
        "net_amount": 6540,
        "amount_to_capture": null,
        "amount_capturable": 0,
        "amount_captured": null
    },
    "customer_id": null,
    "connector": "stripe",
    "created": "2025-06-20T10:58:42.813Z",
    "payment_method_data": {
        "billing": null
    },
    "payment_method_type": "card",
    "payment_method_subtype": "credit",
    "connector_transaction_id": "pi_3Rc2edD5R7gDAGff01vwkClL",
    "connector_reference_id": null,
    "merchant_connector_id": "mca_0GI0dABwex0qdnwlUelt",
    "browser_info": null,
    "error": null,
    "shipping": null,
    "billing": null,
    "attempts": null,
    "connector_token_details": {
        "token": "pm_1Rc2edD5R7gDAGffEOosatGV",
        "connector_token_request_reference_id": "eDuVwDClp0zQPbbkLZ"
    },
    "payment_method_id": null,
    "next_action": {
        "type": "redirect_to_url",
        "redirect_to_url": "http://localhost:8080/v2/payments/12345_pay_01978cfda5fa7c12b1ba298cca0470c2/start-redirection?publishable_key=pk_dev_4499ca4660714d6b83b379218164187a&profile_id=pro_295oknnkIU8LhiO6RTCy"
    },
    "return_url": "https://google.com/success",
    "authentication_type": "three_ds",
    "authentication_type_applied": "three_ds",
    "is_iframe_redirection_enabled": null,
    "merchant_reference_id": null
}
```
Redirect to URL

- Payments Sync
```
curl --location 'http://localhost:8080/v2/payments/12345_pay_01978cfda5fa7c12b1ba298cca0470c2?force_sync=true' \
--header 'x-profile-id: pro_295oknnkIU8LhiO6RTCy' \
--header 'Authorization: api-key=dev_8OKnwsVtu4ZIxxgqDfVQwnQrUfdORX3Ivo9i8Yxp0rB3mEZxiv9UZchQimjPgNnx' \
--data ''
```
Response
```
{
    "id": "12345_pay_01978cfda5fa7c12b1ba298cca0470c2",
    "status": "succeeded",
    "amount": {
        "order_amount": 6540,
        "currency": "USD",
        "shipping_cost": null,
        "order_tax_amount": null,
        "external_tax_calculation": "skip",
        "surcharge_calculation": "skip",
        "surcharge_amount": null,
        "tax_on_surcharge": null,
        "net_amount": 6540,
        "amount_to_capture": null,
        "amount_capturable": 0,
        "amount_captured": 6540
    },
    "customer_id": null,
    "connector": "stripe",
    "created": "2025-06-20T10:58:42.813Z",
    "payment_method_data": {
        "billing": null
    },
    "payment_method_type": "card",
    "payment_method_subtype": "credit",
    "connector_transaction_id": "pi_3Rc2edD5R7gDAGff01vwkClL",
    "connector_reference_id": null,
    "merchant_connector_id": "mca_0GI0dABwex0qdnwlUelt",
    "browser_info": null,
    "error": null,
    "shipping": null,
    "billing": null,
    "attempts": null,
    "connector_token_details": {
        "token": "pm_1Rc2edD5R7gDAGffEOosatGV",
        "connector_token_request_reference_id": "eDuVwDClp0zQPbbkLZ"
    },
    "payment_method_id": null,
    "next_action": null,
    "return_url": "https://google.com/success",
    "authentication_type": "three_ds",
    "authentication_type_applied": null,
    "is_iframe_redirection_enabled": null,
    "merchant_reference_id": null
}
```

Patch:
diff --git a/crates/router/src/core/payments.rs b/crates/router/src/core/payments.rs
index 59de54f41fa..e3fdf6e1cac 100644
--- a/crates/router/src/core/payments.rs
+++ b/crates/router/src/core/payments.rs
@@ -2996,7 +2996,7 @@ impl PaymentRedirectFlow for PaymentRedirectSync {
             force_sync: true,
             expand_attempts: false,
             all_keys_required: None,
-            merchant_connector_details: todo!(), // TODO: Implement for connectors requiring 3DS or redirection-based authentication flows.
+            merchant_connector_details: None, // TODO: Implement for connectors requiring 3DS or redirection-based authentication flows.
         };
 
         let operation = operations::PaymentGet;