feat: add Apple Pay support to Checkout Components (ACC-6923)

[OnurVar]

Summary

Apple Pay flows through the generic usePrimerPaymentMethod('APPLE_PAY') — no bespoke useApplePay hook. It rides the same nativeUi path as Google Pay: the prebuilt method row (or your own button) calls start(), the native Headless SDK presents the sheet, and the outcome arrives on the shared paymentOutcome. Second step of the APM hook unification (after Google Pay, #376).

• Apple Pay is iOS-only: isAvailable is false on Android even if the SDK lists APPLE_PAY — the one Apple-Pay-specific rule, in internal/applePay.ts (mirror of internal/googlePay.ts).
• startNativeUI('APPLE_PAY') rejects when unavailable (e.g. on Android), so a custom layout that skips the isAvailable check still fails safely instead of making a native call.
• No native-bridge or provider re-architecture — the existing Headless NATIVE_UI path already drives Apple Pay. Apple Pay renders as a standard method row (no dedicated native button).

Breaking change

useApplePay and the ApplePayController / ApplePayAvailabilityError types are removed — use usePrimerPaymentMethod('APPLE_PAY') and narrow on kind: 'nativeUi'.

Base

ov/feat/ACC-6923-google-pay-component (#376) — the generic-hook foundation.

Jira

ACC-6923

Test plan

• yarn typecheck / yarn lint — clean
• yarn jest — green; new usePrimerPaymentMethod Apple Pay cases cover iOS availability + start, and the Android guard (unavailable + start() rejects, no native call)
• Manual iOS — Apple Pay in the method list → native sheet → onCheckoutComplete (sandbox payment succeeded)

[OnurVar]

Superseded by the consolidated APM-unification stack — #392 (native-UI) → #393 (bank) → #394 (raw-data) → #395 (QR) → #396 (Klarna). Closing in favor of those; the new stack carries the same work plus the review fixes.