Person page: server-side search; stop loading the whole tree

The person page fetched the entire tree on every open — all persons (to build a
name map + power the relative pickers) and all events (to find partnership
events). On a 2k-person tree that's a ~230KB person list + ~600KB event list per
view. Now it loads only what the page shows:

Frontend:
- The relationship & spouse pickers use the backend's fuzzy pg_trgm search
  (debounced, typo-tolerant) instead of substring-filtering a preloaded array —
  better search, and no need to preload every person. PersonCombobox gained an
  `onSearch` server mode (client `people` mode still works).
- The page drops the all-persons and all-events fetches; it resolves just this
  person's relatives' names via GET /persons?ids=..., and reads partnership
  events from the per-person events endpoint.

Backend:
- GET /trees/{id}/persons?ids=a,b,c — batch by id (privacy-filtered, names
  batched), for relative-name display.
- list_events_for_person (member path) now also returns the person's partnership
  events, so the page needn't scan every event in the tree.

Adversarial review (frontend logic + backend/privacy) found no issues. Suite 105
passing.

Signed-off-by: Justin Paul <justin@jpaul.me>

backend/app/services/person_service.py

@@ -404,6 +404,47 @@ async def list_persons(
     return visible
 
 
+async def list_persons_by_ids(
+    session: AsyncSession, *, viewer_id: uuid.UUID, tree: Tree, ids: list[uuid.UUID]
+) -> list[Person]:
+    """Just the named persons (privacy-filtered, names batched). Lets a page show
+    the names of someone's relatives without loading the whole tree."""
+    role = await privacy.get_membership_role(session, viewer_id, tree.id)
+    if role is None and not await privacy.can_view_tree(session, user_id=viewer_id, tree=tree):
+        raise Forbidden("not permitted to view this tree")
+    if not ids:
+        return []
+    persons = list(
+        (
+            await session.execute(
+                select(Person).where(
+                    Person.id.in_(ids),
+                    Person.tree_id == tree.id,
+                    Person.deleted_at.is_(None),
+                )
+            )
+        ).scalars().all()
+    )
+    if role is not None:
+        await _attach_primary_names(session, persons)
+        return persons
+    visible: list[Person] = []
+    full: list[Person] = []
+    for person in persons:
+        vis = await privacy.person_visibility(
+            session, user_id=viewer_id, tree=tree, person=person
+        )
+        if vis == Visibility.hidden:
+            continue
+        if vis == Visibility.redacted:
+            _redact(person)
+        else:
+            full.append(person)
+        visible.append(person)
+    await _attach_primary_names(session, full)
+    return visible
+
+
 async def search_persons(
     session: AsyncSession, *, viewer_id: uuid.UUID, tree: Tree, query: str, limit: int = 50
 ) -> list[Person]: