fix(react-native): Add use_modular_headers! to iOS Podfile for Swift RNSentry pod

[antonis]

Summary

Re-enables the React Native e2e test on macOS (skipped in #1303) by fixing the underlying pod install failure.

Root cause: As of @sentry/react-native 8.19.0, the RNSentry pod ships Swift code (the RNSentryInternal bridge over SentrySDK.internal, part of the migration to the prebuilt Sentry.xcframework — see sentry-react-native #6413 / #6495). CocoaPods refuses to integrate a Swift pod that depends on a non-modular Objective-C pod (e.g. React-hermes on RN versions that don't modularize it by default) unless the Podfile opts into module maps. So pod install fails with:

[!] The following Swift pods cannot yet be integrated as static libraries:
The Swift pod `RNSentry` depends upon `React-hermes`, which does not define
modules. [...] you may set `use_modular_headers!` globally in your Podfile

The error was masked in CI because pod install --silent only surfaces curl progress, not the CocoaPods error (which is why #1305's --verbose repro was on the right track). This affected real RN users too — the SDK CHANGELOG instructs them to add use_modular_headers! by hand — so the wizard now does it for them.

Changes

• src/react-native/cocoapod.ts: new idempotent addModularHeaders() that inserts use_modular_headers! above the first target block in ios/Podfile (no-op if already present, ignores commented-out targets, logged transparently).
• src/react-native/react-native-wizard.ts: patch the Podfile before pod install whenever the project uses CocoaPods, so the wizard's install and any later manual pod install both work.
• e2e-tests/tests/react-native.test.ts: remove describe.skipIf(darwin) and assert the Podfile gets use_modular_headers!. Fixture Podfile stays vanilla so the test exercises the wizard adding it.
• test/react-native/cocoapod.test.ts: 7 new unit tests for addModularHeaders.
• CHANGELOG.md: entry under Unreleased.

Testing

• Reproduced the exact pod install failure with @sentry/react-native 8.19.0 on the RN 0.78 test app (exit 1); confirmed use_modular_headers! fixes it (exit 0).
• Full RN e2e test passes on macOS (11/11) — the wizard logs adding the line, then Pods installed. succeeds.
• test/react-native/ unit tests: 140/140. yarn build and yarn lint clean.

🤖 Generated with Claude Code

[msonnb]

nice, thank you!