Fix: Event session cold-start bug - presentations/presenters now load on first render

CRITICAL BUG FIX: Session view required 1-2 manual refreshes to display
presentations and presenters when IndexedDB was empty.

Root Cause:
- Nested loaders passed try_cache: false, preventing IDB writes
- Missing microtask yields caused race conditions between IDB writes
  and liveQuery subscriptions

Changes:
- ae_events__event_session.ts: Preserve try_cache in nested loads
- ae_events__event_presentation.ts: Block on presenter loads with await
  Promise.all() + preserve try_cache
- ae_events__event_presenter.ts: Add microtask yield after IDB write

Result: Presentations AND presenters now render correctly on first
navigation without requiring manual page refresh.

src/lib/ae_events/ae_events__event_presenter.ts

@@ -134,7 +134,7 @@ async function _refresh_presenter_li_background({ api_cfg, for_obj_type, for_obj
         const result_li = await api.get_ae_obj_li_v3({ api_cfg, obj_type: 'event_presenter', for_obj_type, for_obj_id, enabled, hidden, view, limit, offset, order_by_li, log_lvl });
         if (result_li) {
             const processed = await process_ae_obj__event_presenter_props({ obj_li: result_li, log_lvl });
-            
+
             // String-Only ID Vision: Ensure linking ID is set for indexing
             processed.forEach((p) => {
                 if (for_obj_type === 'event_presentation') {
@@ -153,6 +153,10 @@ async function _refresh_presenter_li_background({ api_cfg, for_obj_type, for_obj
 
             if (try_cache) {
                 await db_save_ae_obj_li__ae_obj({ db_instance: db_events, table_name: 'presenter', obj_li: processed, properties_to_save, log_lvl });
+                // CRITICAL FIX (2026-02-26): Yield to microtask queue so Dexie liveQuery observers
+                // fire before we return. Without this, component-mounted liveQueries may subscribe
+                // to IDB *before* the write completes, causing empty results on cold-start.
+                await Promise.resolve();
             }
 
             // Background nested loads for refreshed items (FIRE AND FORGET)