fix(launcher): break reactive loop causing tab crash on Event Files

The $effect in launcher_presentation_view.svelte was calling
load_ae_obj_id__event_presentation() on every prop update. The SWR
pattern in that function always fires a background Dexie write, which
triggered the upstream liveQuery, which updated the prop, which
re-ran the $effect — creating an infinite loop that saturated the API
and crashed the browser tab within 30-60 seconds.

Fix: guard on last_loaded_id so the API call only fires when the
presentation ID actually changes, not on every downstream re-render.

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

src/routes/events/[event_id]/(launcher)/launcher_presentation_view.svelte

@@ -12,10 +12,18 @@
     import { events_func } from '$lib/ae_events_functions';
     import Event_launcher_file_cont from './launcher_file_cont.svelte';
 
-    // Staggered Load: Trigger deep fetch only when component is active
+    // Staggered Load: Trigger deep fetch only when the presentation ID changes.
+    // WHY: The SWR pattern in load_ae_obj_id__event_presentation always fires a
+    // background API call that writes to Dexie. That Dexie write triggers the
+    // liveQuery upstream, which updates the lq__event_presentation_obj prop,
+    // which re-runs this $effect — creating an infinite loop that crashes the tab.
+    // Guarding on last_loaded_id breaks the loop: the effect only makes an API
+    // call when we see a new presentation ID, not on every downstream prop update.
+    let last_loaded_id: string | null = null;
     $effect(() => {
         const id = lq__event_presentation_obj?.event_presentation_id;
-        if (id) {
+        if (id && id !== last_loaded_id) {
+            last_loaded_id = id;
             events_func.load_ae_obj_id__event_presentation({
                 api_cfg: $ae_api,
                 event_presentation_id: id,