[2025-10] Backport auto POS button variant

[henryStelle]

Summary

Backports #4625 to the 2025-10 stable branch.

• allow the public POS s-button variant type to explicitly accept auto
• keep the individual and aggregate component declarations consistent
• regenerate the tracked 2025-10 POS docs JSON
• add an @shopify/ui-extensions patch changeset

Issue: https://github.com/shop/issues-retail/issues/33323

Validation

• yarn docs:point-of-sale 2025-10
• yarn build
• direct TypeScript validation assigning variant: 'auto' to ButtonJSXProps
• yarn type-check
• yarn lint
• No relevant automated test suite is present for this declaration-only POS type change.
• shopify validate components was not run because the Shopify CLI is unavailable in this environment.

[henryStelle]

This PR backports #4625 to the 2025-10 stable branch.

[henryStelle]

Regenerated the 2025-10 JSON after adding the missing auto item to that version's detailed variant option list. The matching Shopify.dev sync is in https://github.com/shop/world/pull/998654.