Align CI and release builds on Xcode 27

[austin-smith]

What Changed

• Run lint, macOS tests, iOS builds, and releases on the same xcode-27 runner image.
• Use the runner-selected xcodebuild command in CI and update the existing widget documentation sentence.

Why

The iOS build used the Xcode 27 runner while macOS validation and releases used macos-26. Aligning the runner image keeps validation and distribution on the same toolchain family. Deployment targets remain iOS/macOS 26.

Validation

• Both workflow YAML files parse; Actionlint and git diff --check pass. The documented xcode-27 label was configured locally because Actionlint does not yet include it in its bundled label list.
• Unsigned arm64 macOS Release archive passed locally on Xcode 27.1.
• Hosted execution and signed release export/notarization have not run for this change.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-19T03:46:15.400417Z	36a4650	Draft marked ready

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.