fix(pack): tutorial pack_open ThenIncludes OwnedItemEntry.Item

Without .ThenInclude(i => i.Item), the OwnedItemEntry.Item nav defaults to a
new ItemEntry() with Id=0 (project_ef_nav_include_pitfall), so the
FirstOrDefault(i => i.Item.Id == ticketItemId) lookup never matched. The
ticket was never decremented and reward_list omitted the post-state entry —
on the next /tutorial/pack_info the pack stayed visible and the client
re-clicked into plain /pack/open, which 501s on type_detail=5.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Controllers/PackController.cs

@@ -183,7 +183,7 @@ public class PackController : SVSimController
         var viewer = await _db.Viewers
             .Include(v => v.PackOpenCounts)
             .Include(v => v.MissionData)
-            .Include(v => v.Items)
+            .Include(v => v.Items).ThenInclude(i => i.Item)
             .AsSplitQuery()
             .FirstAsync(v => v.Id == viewerId);
         int packNumber = Math.Max(1, request.PackNumber);