Update repo for 3.38

[stuartmorgan-g]

Does all of the steps from https://github.com/flutter/flutter/blob/master/docs/ecosystem/release/Updating-Packages-repo-for-a-stable-release.md for the 3.38 release (except the first one, which the stable roller will handle).

This includes a lot of autoformat changes, because the N-2 is now 3.32, which means many packages are now being updated to a min Dart SDK of 3.8, triggering a formatter behavior change.

[stuartmorgan-g]

Version override: min SDK changes are one of the documented exceptions for version bumps. (The formatter changes are technically changes to production code, but it's just autoformatting so there's no real value in releasing it.)

[gemini-code-assist]

Code Review

This pull request updates the repository for the 3.38 release. The changes include updating CI configurations, bumping the minimum SDK and Flutter versions in various pubspec.yaml files, and adding release notes to CHANGELOG.md files. A significant portion of the changes consists of code reformatting, which is expected due to the Dart SDK update. All modifications appear to be correct and align with the goal of preparing the repository for the new Flutter version.

[mdebbar]

RSLGTM

[Piinks]

LGTM!

[parlough]

mustache_template changes look good to me, thanks!