Commerce Simplenews Checkout integration

Adds a Drupal Commerce Checkout Pane implementation for Simplenews. This makes it possible to subscribe to the websites newsletters in the checkout progress.

Core use case

Allow customers to subscribe to Simplenews newsletters during the checkout process in Drupal Commerce.

Key Functionality:

Checkout Integration – Adds a newsletter subscription option directly to the Commerce checkout form.

• Simplenews Compatibility – Works with the Simplenews module, allowing customers to opt into newsletters when placing an order.
• Optional Subscription – Customers can choose whether or not to subscribe (configurable as required/optional).
• Automatic Subscription Handling – If selected, the customer is automatically subscribed to the configured Simplenews mailing list upon successful order completion.

Typical Use Case Scenario:

• An e-commerce site sells products and wants to grow its newsletter subscriber base.
• During checkout, customers see a checkbox (e.g., "Subscribe to our newsletter").
• If checked, the customer’s email is added to a Simplenews mailing list after purchase, without requiring a separate signup process.

This module bridges Drupal Commerce and Simplenews, streamlining marketing efforts by capturing newsletter signups at the point of sale.