PayPal Payments abilities: register button reads via Registrar

[enejb]

Summary

• Adds jetpack-paypal-payments/list-buttons ability to the packages/paypal-payments package, exposing PayPal Simple Payments buttons (jp_pay_product posts) through the WordPress Abilities API.
• list-buttons accepts status (publish/draft/all), search, page, per_page (1-100), and button_id (single-button short-circuit so a separate get-button reader isn't needed). Output: { id, title, price, currency, recipient_email, button_image_url, edit_url, status, created_at }.
• Read-only. create-button / update-button / delete-button are deliberately deferred.
• Wired via packages/paypal-payments/actions.php and gated behind Registrar::init()'s jetpack_wp_abilities_enabled filter (default false), so the abilities surface in both the standalone PayPal Payment Buttons plugin and Jetpack core consumers, but rollout stays opt-in per site.
• Permission gate: current_user_can( 'edit_posts' ), matching the jp_pay_product CPT's capability map.
• Plan reference: §4.2 (PayPal payment buttons logic lives in packages/paypal-payments; plugin is a thin wrapper) and §2.10 (gated registrar pattern).

Test plan

• composer phpunit -- --filter PayPal_Payments_Abilities_Test — 19 tests, 43 assertions, all green.
• Full package suite stays green (44 tests, 85 assertions).
• PHPCS clean on the new files.
• Confirm in a Jetpack / PayPal Payment Buttons site (with jetpack_wp_abilities_enabled flipped to true) that GET /wp-json/wp-abilities/v1/abilities/jetpack-paypal-payments/list-buttons returns the expected entries for an editor user.

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (Jetpack), and enable the add/ship-paypal-payments-abilities branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack add/ship-paypal-payments-abilities

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

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[jp-launch-control]

Code Coverage Summary

1 file is newly checked for coverage.

File	Coverage
projects/packages/paypal-payments/src/abilities/class-paypal-payments-abilities.php	144/146 (98.63%) 💚

Full summary · PHP report · JS report