fix(launcher): sort presentations by priority > sort > start_datetime > code > name

Replaced single-field sortBy() (poster→name, oral→start_datetime) with
toArray() + JS comparator matching the same sort chain as Pres Mgmt.
Removes the sort_by branch since the comparator handles both session types.

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

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

@@ -90,11 +90,12 @@ let lq__event_file_obj_li = $derived.by(() => {
 });
 
 // Event Presentation
-// WHY: $derived.by — same reason as above. Captures both id and sort_by in the outer
+// WHY: $derived.by — captures id in the outer closure so a new Observable is
-// closure so a new Observable is created whenever the session or its type changes.
+// created whenever the session changes. Multi-field sort requires toArray() + JS
+// comparator since Dexie's sortBy() is single-field only.
+// Order: priority DESC → sort ASC → start_datetime ASC → code ASC → name ASC
 let lq__event_presentation_obj_li = $derived.by(() => {
     const id = slct__event_session_id;
-    const sort_by = type_code == 'poster' ? 'name' : 'start_datetime';
     return liveQuery(async () => {
         if (!id) return [];
 
@@ -102,10 +103,32 @@ let lq__event_presentation_obj_li = $derived.by(() => {
             console.log(`[LQ] Fetching presentations for session: ${id}`);
         }
 
-        return await db_events.presentation
+        const results = await db_events.presentation
             .where('event_session_id')
             .equals(id)
-            .sortBy(sort_by);
+            .toArray();
+        return results.sort((a, b) => {
+            // priority DESC (true first)
+            const pa = a.priority ? 1 : 0;
+            const pb = b.priority ? 1 : 0;
+            if (pb !== pa) return pb - pa;
+            // sort ASC
+            const sa = a.sort ?? 0;
+            const sb = b.sort ?? 0;
+            if (sa !== sb) return sa - sb;
+            // start_datetime ASC
+            const da = a.start_datetime ?? '';
+            const db_val = b.start_datetime ?? '';
+            if (da !== db_val) return da < db_val ? -1 : 1;
+            // code ASC
+            const ca = a.code ?? '';
+            const cb = b.code ?? '';
+            if (ca !== cb) return ca < cb ? -1 : 1;
+            // name ASC
+            const na = a.name ?? '';
+            const nb = b.name ?? '';
+            return na < nb ? -1 : na > nb ? 1 : 0;
+        });
     });
 });