fix: preserve camelCase keys and numeric values in merchant session validation

[aritro2002]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

Fixes two related bugs in Apple Pay merchant session validation that caused onvalidatemerchant to fail.

Problem

The Apple Pay session token data returned from the backend is already in camelCase (e.g. epochTimestamp, merchantSessionIdentifier). When transformKeys(CamelCase) was applied:

1. toCamelCase called String.toLowerCase unconditionally before applying the camelCase regex. Since the regex only capitalizes letters after _ or -, keys without separators were fully lowercased (epochTimestamp → epochtimestamp), causing Apple Pay's completeMerchantValidation to fail with malformed session data.
2. transformKeys coerces all Number values to strings (val->Float.toString), corrupting numeric fields like epochTimestamp and expiresAt that Apple Pay expects as integers.
   Changes

• toCamelCase / toCamelCaseWithNumberSupport (Utils.res): Only apply the lowercase + regex transform when the string contains _ or -. Otherwise pass through as-is (stripping non-alpha characters only), preserving existing camelCase keys.
• startApplePaySession (ApplePayHelpers.res): Replace transformKeys(CamelCase) with transformKeysWithoutModifyingValue(CamelCase) so numeric values remain as numbers instead of being stringified.
  Testing
• Verify Apple Pay merchant validation succeeds end-to-end on a supported device/browser
• Verify snake_case → camelCase conversion still works correctly for other use cases of transformKeys

How did you test it?

I have tested it locally, by comparing the merchant session before and after transformation and also e2e testing.

before:

after:

Screen.Recording.2026-05-19.at.5.47.57.pm.mov

Checklist

• I ran npm run re:build
• I reviewed submitted code
• I added unit tests for my changes where possible

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