feat(normalizer): build_given_names from register + supplement

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tools/import-normalizer/persons.py

@@ -197,6 +197,22 @@ def classify_name(raw: str, given_names: set[str]) -> NameClass:
 # register; if they surface in review, lower-priority than the real prose entries.
 
 
+def build_given_names(register: list[Person], extra: set[str]) -> set[str]:
+    """Set of normalized given names from the register (first + extra given) plus a supplement.
+
+    Used by classify_name to tell a two-given-name pair (two people) from a first+surname.
+    """
+    names: set[str] = set()
+    for p in register:
+        if p.first_name:
+            names.add(_norm(p.first_name))
+        for g in p.extra_given_names:
+            names.add(_norm(g))
+    for e in extra:
+        names.add(_norm(e))
+    return names
+
+
 class AliasIndex:
     def __init__(self, people: list[Person]):
         self._by_alias: dict[str, str] = {}