[SandObserver]

Summary

• Allow OFL-*.txt font licence files through the demo upload's web-files check. The Clock widget ships three of them next to its fonts.
• Add a repository test that every .txt file under ui/ matches that name, so a new text file fails the tests before it fails a release.

Testing
All green. Added 1 test; it fails when a stray .txt file is added under ui/.

Changelog

Checklist

• Stays within the project constraints: one container, no runtime dependencies, no build step (see CONTRIBUTING.md).
• Tests added or updated for new logic, and the full suite, lint, and typechecks pass.
• Docs updated if behavior or configuration changed.