fix: pres_mgmt session search now includes presenter and presentation names

Previously, searching by presenter name in pres_mgmt returned no results
because event_presenter_li_qry_str / event_presentation_li_qry_str were
never requested or stored.

Changes:
- ae_types.ts: add event_presentation_li_qry_str + event_presenter_li_qry_str
  to ae_EventSession interface
- db_events.ts: same two fields added to Session Dexie interface
- ae_events__event_session.ts:
  * add ft_presentation_search_qry_str param
  * auto-upgrade view to 'alt' when either ft_presenter or ft_presentation
    search is used (backend requires v_event_session_w_file_count for these)
  * add both fields to properties_to_save so they persist to Dexie cache
- +page.svelte (pres_mgmt):
  * pass ft_presenter_search_qry_str + ft_presentation_search_qry_str in API call
  * local IDB fast path now checks both new fields
  * client-side filter guard also checks both new fields

src/lib/ae_events/db_events.ts

@@ -809,6 +809,9 @@ export interface Session {
     // A key value list of the presentations
     event_presentation_kv?: null | key_val;
     event_presentation_li?: null | [any];
+    // Concatenated search strings from JOINed views (v_event_session_w_file_count)
+    event_presentation_li_qry_str?: null | string;
+    event_presenter_li_qry_str?: null | string;
     // A key value list of the files
     event_file_kv?: null | key_val;
     event_file_li?: null | [any];