Add fuzzy name search (pg_trgm) and living-person protection

Fuzzy search: pg_trgm extension + trigram GIN indexes on name parts and a GET /trees/{id}/persons?q= search ranked by trigram similarity (finds Mueller for 'muller'), privacy-filtered. Living-person protection: the privacy engine now derives possibly-living status (explicit flag, else no death fact + birth within ~100y or unknown) and returns 'redacted' for non-members of public/unlisted trees; the service minimises those records ('Living person', no vitals). Members are unaffected. 31 tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

backend/app/api/v1/persons.py

@@ -36,10 +36,18 @@ async def create_person(
 
 @router.get("/{tree_id}/persons", response_model=list[PersonRead])
 async def list_persons(
-    tree_id: uuid.UUID, session: SessionDep, current: CurrentUser, deleted: bool = False
+    tree_id: uuid.UUID,
+    session: SessionDep,
+    current: CurrentUser,
+    deleted: bool = False,
+    q: str | None = None,
 ) -> list[PersonRead]:
     tree = await tree_service.get_tree(session, viewer_id=current.id, tree_id=tree_id)
-    if deleted:
+    if q:
+        persons = await person_service.search_persons(
+            session, viewer_id=current.id, tree=tree, query=q
+        )
+    elif deleted:
         persons = await person_service.list_deleted_persons(
             session, viewer_id=current.id, tree=tree
         )