fix(paypal): handle zero-decimal currencies (JPY) during order creation (#29983)

[jihadMo]

Closes #29983

Summary of Changes

• Uses convertFromSmallestToPresentableCurrencyUnit(amount, currency) from @calcom/lib/currencyConversions when constructing PayPal order purchase unit amounts in packages/app-store/paypal/lib/Paypal.ts.
• Fixes critical pricing bug where zero-decimal currencies (such as Japanese Yen / JPY) were divided by 100, causing PayPal to collect only 1/100th of the organizer's configured price (e.g. ¥100 instead of ¥10,000).
• Preserves standard minor-unit conversions for decimal currencies (USD, EUR, GBP, etc.).

Verification

• Verified against @calcom/lib/currencyConversions:
  • JPY: 10000 -> "10000" (sent as full unscaled unit)
  • USD: 5000 -> "50" (sent as $50.00)

[github-actions]

Welcome to Cal.diy, @jihadMo! Thanks for opening this pull request.

A few things to keep in mind:

• This is Cal.diy, not Cal.com. Cal.diy is a community-driven, fully open-source fork of Cal.com licensed under MIT. Your changes here will be part of Cal.diy — they will not be deployed to the Cal.com production app.
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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 00a0c30b-4e43-4571-8c6a-0bdda74f4766

📥 Commits

Reviewing files that changed from the base of the PR and between 176037d and a556e37.

📒 Files selected for processing (1)

• packages/app-store/paypal/lib/Paypal.ts

Included review availability: Your plan provides up to 10 included reviews per hour; 9 remain after this review.

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📝 Walkthrough

Walkthrough

PayPal order creation now uses convertFromSmallestToPresentableCurrencyUnit(amount, currency) to convert amounts from smallest currency units. The previous fixed division by 100 is replaced. The required currency conversion utility is imported.

Merge Risk: ⚪ Minimal · up to a556e

The PR updates PayPal order amount conversion for zero-decimal currencies while preserving decimal-currency behavior. No actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the PayPal fix for zero-decimal currencies during order creation.
Description check	✅ Passed	The description directly explains the currency conversion change, the JPY pricing bug, and verification results.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[CLAassistant]

All committers have signed the CLA.