feat(stores): promote events auth state to Svelte 5 PersistedState

Creates ae_events_stores__auth.svelte.ts with PersistedState keyed
'ae_events_auth_loc' for auth__person and auth__kv (presenter/session
sign-in state). Migrated 10 component files from $events_loc.auth__* to
events_auth_loc.current.auth__*.

Also fixed stale pres_mgmt stragglers: $events_loc.pres_mgmt.* refs in
presenter_obj_li.svelte, presenter_page_menu.svelte, and [presenter_id]/
+page.svelte now use pres_mgmt_loc.current.* directly.

show_details boolean moved from events_loc to leads_loc (it belongs in
the leads module — one bind in ae_tab__manage.svelte).

auth__person, auth__kv, show_details, events_cfg_json, event_id removed
from events_local_data_struct. events_loc now only carries ver, title,
and qry__* prefs.

svelte-check: 0 errors, 0 warnings.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/routes/events/[event_id]/(leads)/leads/exhibit/[exhibit_id]/ae_tab__manage.svelte

@@ -7,7 +7,7 @@ import { page } from '$app/state';
 import { liveQuery } from 'dexie';
 import { db_events } from '$lib/ae_events/db_events';
 import { ae_api, ae_loc } from '$lib/stores/ae_stores';
-import { events_loc, events_sess } from '$lib/stores/ae_events_stores';
+import { events_sess } from '$lib/stores/ae_events_stores';
 import { leads_loc } from '$lib/stores/ae_events_stores__leads.svelte';
 import { events_func } from '$lib/ae_events/ae_events_functions';
 import Element_ae_obj_field_editor from '$lib/elements/element_ae_obj_field_editor.svelte';
@@ -605,7 +605,7 @@ function handle_signout() {
                         <input
                             type="checkbox"
                             class="checkbox"
-                            bind:checked={$events_loc.show_details} />
+                            bind:checked={leads_loc.current.show_details} />
                     </label>
                 </div>
             </div>