Add repository attribution policy gate

[bt1142msstate]

Summary

• add a fast repository policy workflow for every push and pull request
• scan branch and tag names, pull request and release metadata, commit messages, changed history, tracked paths, and tracked file contents
• construct the two prohibited attribution terms at runtime so the policy does not add them to public source or history
• add architecture coverage for case-insensitive text and byte scanning

Validation

• repository policy check passed
• lint passed
• architecture suite: 15 tests passed
• unit suite: 287 tests passed