Say what actually counts as a rival, now that a name anchors too

assign's denominator is the identities the user has ruled on, and it
reads Cluster::person to find them. Master's "Let a name hold a group
together" widened what sets that field: a confirmation, a name, or an
ignore, where before it was a confirmation alone.

The behaviour is right either way — a named person is exactly the
identity a suggestion should be discounted against — but the module note
and faces.md §9.1 both said "a confirmation", which is now too narrow.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/faces.md

@@ -758,9 +758,10 @@ equally well land at 0.5 each, which is the truth about a sibling.
 **Only named people compete, and they compete per person.** This is the part that had to be measured
 rather than reasoned about. Normalising across *every* group made the number useless on a real
 18,000-face library — median suggestion 21%, four in five under half — because clustering leaves one
-person spread across many groups, so a face competes against itself. Counting only groups holding a
-confirmation fixed most of it; counting them **per person** rather than per group fixed the rest,
-since a named person is left in several anchored groups for the same reason.
+person spread across many groups, so a face competes against itself. Counting only the groups the user has
+ruled on — one holding a confirmation, a name, or an ignore — fixed most of it; counting them **per
+person** rather than per group fixed the rest, since one person is left in several anchored groups
+for the same reason.
 
 **Rivals are gathered below the merge threshold**, down to even odds: a named person who matches at
 0.6 will never be merged into but is exactly the competition a suggestion should be discounted for.