[chrfalch]

Summary

Depends on #59742. This PR is based on that branch and shows only its own commit.

npx react-native spm deinit takes an app from SwiftPM back to CocoaPods. No CI job tests this today. The unit tests mock pod and xcodebuild, and no job runs deinit. A later change could break the way back without any failing check.

This PR adds a file check to the template app build job (e2e-ios-templateapp.yml, Debug and Release):

1. Before spm add, the job records the sha256 of ios/Podfile and ios/.gitignore, or absent when .gitignore is missing.
2. After the app upload, the job runs npx react-native spm deinit. The uploaded app is not affected.
3. .github/workflow-scripts/assert-spm-deinit.sh then checks:
   • the Podfile is byte-identical;
   • .gitignore is byte-identical, or gone if it was absent before;
   • the .spm-injected.json marker and ios/ReactNativeSPM/ are gone;
   • project.pbxproj has no SwiftPM package references, product dependencies, ReactNativeSPM paths, or SwiftPM build phases;
   • no shared scheme still has the SwiftPM pre-action.

The check reads files only. deinit does not run pod install, so the steps take seconds. CocoaPods references are not checked, because pod install restores those, not deinit.

Changelog:

[INTERNAL] [ADDED] - CI check that spm deinit takes the template app back to CocoaPods

Test Plan:

I ran the script locally on copies of private/helloworld/ios with a test Podfile:

• No deinit: the script fails with one error for each SwiftPM change still in place.
• A copy of deinit that I changed to keep the marker, a copy that keeps one .gitignore line, and a copy that keeps the scheme pre-action: each fails on exactly that check.
• Real deinit, with .gitignore absent before add and with an existing .gitignore: the script passes, and .gitignore is byte-identical.
• bash -n passes on the script, and the workflow YAML parses.

Not run: shellcheck (not installed locally), and the job itself. CI on this PR runs it.