Add an optional findings[].domain field to the DO review output contract so
each finding carries its own human-readable review-domain display label. Leaf
review skills set it on every finding they emit; the al-code-review super-skill
copies it verbatim during rollup and sets it to "Agent" for its own
cross-cutting agent findings. This decouples consumers from BCQuality's domain
taxonomy: they render finding.domain verbatim instead of maintaining a
sub-skill-id -> label map.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>