fix: guard Paddle checkout item updates

[rebelchris]

Summary

• Guard Paddle Checkout.updateItems until the inline checkout iframe is mounted.
• Reopen the inline checkout when a responsive remount leaves Paddle with stale iframe state.
• Add regression tests for the remount path and Paddle contentWindow exception recovery.

Testing

• NODE_ENV=test ./node_modules/.bin/jest src/hooks/usePaddlePayment.spec.tsx --runInBand
• node ./scripts/typecheck-strict-changed.js
• ./node_modules/.bin/eslint src/hooks/usePaddlePayment.ts src/hooks/usePaddlePayment.spec.tsx --max-warnings 0

Refs dailydotdev/daily#2115

Preview domain

https://codex-fix-paddle-checkout-remoun.preview.app.daily.dev

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Project	Deployment	Actions	Updated (UTC)
daily-webapp	Ready	Preview	May 21, 2026 12:43pm

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
storybook	Ignored		May 21, 2026 12:43pm