Add 'source.wallet' column to payments exports for Apple Pay / Google Pay

🔍 Problem Statement

Currently, there is no way to differentiate between Apple Pay payments and normal card payments in the exports. While this information is visible in the Payment section, it is not reflected in the exported data, limiting clients’ ability to track and analyze payment methods.

👤 User Story

As a Pelcro client, I want to see whether a payment was made using Apple Pay, Google Pay, or a normal card in the export files, so that I can analyze payment behavior and reconcile transactions more accurately.

🎯 Definition of Done (DoD)

A feature is done when:

✔️ A new column is added at the end of the payments export to display the type of the online payment method.
✔️ The column is named source.wallet.
✔️ The column supports identifying Apple Pay and Google Pay across all payment gateways that provide this information.
✔️ Normal card payments continue to be displayed as-is (no disruption to existing data).

Test Cases:

1. Column placement

Scenario: Generate a payments export.
Expected Result: A new column named source.wallet appears at the end of the export file, after all existing columns.

2. Apple Pay transaction

Scenario: Process a payment using Apple Pay and generate a payments export.
Expected Result: The source.wallet column is populated with apple_pay for that transaction.

3. Google Pay transaction

Scenario: Process a payment using Google Pay and generate a payments export.
Expected Result: The source.wallet column is populated with android_pay for that transaction.

4. Normal card transaction

Scenario: Process a payment using a regular credit/debit card and generate a payments export.
Expected Result: The source.wallet column is blank, and existing card data remains unchanged.

5. Mixed transactions

Scenario: Export a file containing Apple Pay, Google Pay, and normal card transactions together.
Expected Result: The source.wallet column accurately reflects apple_pay, android_pay, or is blank for each transaction, and all existing data is preserved.