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>

core/dr-face/src/assign.rs

@@ -58,9 +58,10 @@
 //! and the better covered the person, the more fragments there are to lose to.
 //!
 //! A fragment is not a rival. An identity the user has actually asserted is, so
-//! the denominator counts only people a confirmation names ([`Cluster::person`])
-//! — and counts them **per person, not per group**, since a named person is
-//! left in several anchored groups for the same reason. Keying it by group had
+//! the denominator counts only the people they have ruled on — a group carries
+//! a [`Cluster::person`] when it holds a confirmation, a name, or an ignore —
+//! and counts them **per person, not per group**, since one person is left in
+//! several anchored groups for the same reason. Keying it by group had
 //! Catherine competing with Catherine and put the median suggestion onto a
 //! named person at 39%; keying it by person put it at 99.5%.
 //!
@@ -209,10 +210,11 @@ pub fn identity_shares(faces: usize, clusters: &[Cluster], pairs: &[Pair], top:
                 ours = score;
                 coherence = score / counted as f32;
             } else if matches!(who, Identity::Person(_)) {
-                // Only an identity the user has asserted competes. An unnamed
-                // group that matches this face is far more likely to be another
-                // fragment of the same person than a different one — see the
-                // module note, and the library it was measured on.
+                // Only an identity the user has ruled on competes. A group
+                // nobody has ruled on and that matches this face is far more
+                // likely to be another fragment of the same person than a
+                // different one — see the module note, and the library it was
+                // measured on.
                 rivals += score;
             }
         }