Switch Scribe-i18n from git subtree to git submodule

[catreedle]

Terms

• I have searched open and closed issues
• I agree to follow Scribe-Android's Code of Conduct

Issue

We are moving Scribe-i18n from a git subtree to a git submodule across Scribe-Android, Scribe-iOS, and scri.be.

This change allows contributors to work on i18n keys and values directly while developing features, commit and push changes to the Scribe-i18n repository, and keep translation updates closely aligned with feature work.

Works include removing the existing subtree, adding Scribe-i18n as a submodule, updating contributor documentation, and ensuring CI/build pipelines support submodules.