fix(react-paypal-js): preserve Braintree options and clean up checkout instances

[OskarEichler]

Fixes

• Forward all supported hook props from the one-time and checkout-with-vault buttons. This restores shippingCallbackUrl on both and shippingAddressOverride on the one-time button; removes two duplicated prop lists that omitted options added by Feature: BT-PayPal Pay Later hook #936.
• Own each v6 checkout instance within its initialization effect. Close late-created instances and instances whose SDK loading fails or finishes after unmount. Wait for initialization to settle before teardown, close once, and contain teardown rejections.
• Reject a legacy Braintree namespace if either required factory is missing, rather than only when both are missing.

Compatibility

No public API/type changes. Shipping options already accepted by the button types now reach the SDK. Incomplete legacy namespaces fail early with the existing descriptive error. No new payment/capture behavior or client-instance ownership changes.

Verification

React 19/JSDOM mocked-SDK reproductions cover unmount during checkout creation, unmount during SDK load, normal unmount and SDK-load failure: each instance closes once (previously three of these leaked). Button-to-session option capture confirms restored shipping props, with billing-agreement behavior unchanged. Both partially populated legacy namespaces are rejected.

Combined reviewed patch set: existing React suite has 914 passes, 2 pre-existing HostedFieldsProvider failures and 17 passing snapshots, identical to unmodified main. Lint/typecheck, Rollup builds, declarations and diff/format checks pass (five existing JSDoc warnings). No live Braintree/PayPal transactions. No test files changed.

[changeset-bot]

🦋 Changeset detected

Latest commit: 09ec145

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@paypal/react-paypal-js	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR