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>

frontend/lib/api/schema.d.ts

@@ -2719,6 +2719,7 @@ export interface operations {
             query?: {
                 deleted?: boolean;
                 q?: string | null;
+                ids?: string | null;
             };
             header?: never;
             path: {