feat: add PrimerPaymentMethodList and checkout flow (ACC-6492)

[OnurVar]

Summary

Drop-in UI for the new Checkout Components SDK.

• PrimerPaymentMethodList — renders payment method buttons from usePaymentMethods(). Card renders outlined with "Pay with card"; other methods render as filled logo buttons, with per-method surcharge and include/exclude filtering. Pass data to bypass the hook when methods are already fetched.
• PrimerCheckoutSheet — opinionated wrapper that composes CheckoutSheet with CheckoutFlow so merchants get the whole thing in one component.
• CheckoutFlow — shows LoadingScreen until the SDK is ready, then transitions to MethodSelectionScreen.
• MethodSelectionScreen — localized "Choose payment method" header, auto-sizing sheet height, bottom-inset and drag-handle spacing reserved.
• CheckoutSheet — fixes the open animation being skipped when the component mounts with visible=true (prevVisibleRef was seeded from the current value).
• Example app: new "Checkout Components" screen creates a session and opens the sheet.

Jira

ACC-6492

Test plan

• yarn lint
• yarn typecheck
• yarn test — 85/85
• Tap "Checkout Components" → "Default" → sheet opens with loading, then shows method list
• Cancel button dismisses the sheet
• Backdrop tap dismisses the sheet
• Sheet height scales to the number of methods

[github-actions]

	Warnings
⚠️	This PR doesn't seem to contain any updated Unit Test for Swift 🤔. Please consider double checking it 🙏

	Messages
📖	✅ No SwiftLint violations found.

Generated by 🚫 Danger Swift against c42b7c5

[github-actions]

	Warnings
⚠️	This PR doesn't seem to contain any updated Unit Test for Kotlin 🤔. Please consider double checking it 🙏

	Messages
📖	✅ No detekt violations found.

Generated by 🚫 Danger Kotlin against c42b7c5

[unblocked]

2 issues found.

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[github-actions]

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[github-actions]

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[sonarqubecloud]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

[github-actions]

	Warnings
⚠️	Pull Request size seems relatively large. If this Pull Request contains multiple changes, please split each into separate PRs for a faster, easier review.

	Messages
📖	✅ No ESLint violations found.

Generated by 🚫 dangerJS against c42b7c5