Fix Expo 56 LinkKit pod install

[dtroupe-plaid]

Summary

• Fixes Expo SDK 56 iOS prebuild/pod install failures caused by the npm-packed LinkKit.xcframework losing Mac Catalyst framework symlinks.
• Replaces the bundled LinkKit artifact with an iOS-only XCFramework containing ios-arm64 and ios-arm64_x86_64-simulator.
• Adds LinkKit validation and Catalyst stripping scripts, plus CI coverage for framework slices/signatures and Expo SDK 56 iOS prebuild from the packed SDK.

Motivation

Fixes #931.

The published package included a Mac Catalyst slice whose framework symlinks were omitted by npm pack. CocoaPods validates all XCFramework slices, even when Catalyst is disabled, so it treated the broken Catalyst slice as static and failed with:

Unable to install vendored xcframework `LinkKit` for Pod `ReactNativePlaidLinkSdk`, because it contains both static and dynamic frameworks.

Testing

• npm run check:linkkit
• npm run check:package
• npm run lint
• npm pack --json
• npx prettier --check .github/workflows/pull_request.yml README.md package.json scripts/check-package-entrypoints.js scripts/validate-linkkit-xcframework.js scripts/strip-linkkit-maccatalyst.js
• Parsed .github/workflows/pull_request.yml with Ruby YAML.
• Validated a local Expo SDK 56 / React Native 0.85.3 app using the packed SDK tarball:

npx expo prebuild --platform ios --clean

Result:

✔ Installed CocoaPods

[github-actions]

Coverage after merging codex/fix-issue-931-linkkit-xcframework into master will be

100.00%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
ReactNativePlaidLinkSdkModule.ts	100%	100%	100%	100%
index.ts	100%	100%	100%	100%