brand: sweep remaining umbra refs -> Signetry

[bkd-dotcom]

Fix leftover lowercase brand refs (CLI user-facing strings, test function names). 45 tests pass.

[github-actions]

Umbra Reviewer — 🟡 Needs human review

A human should decide — the required check is unknown.

Deterministic gates (the authority)

Gate	Status
Required status check	— unknown
Secret scan	✅ clean
CI permission / OIDC	✅ no forbidden change
Dependency skew	✅ ok
All green	❌

Findings

No issues found by the deterministic scanners.

Merge

A human should review and merge.

This review is advisory. It never merges on its own judgement — the deterministic gates + a human are the authority. Findings can have false negatives; a green bot verdict is not a guarantee.