Update wire protocol to version 5, introducing pupil slots and item counts in map snapshots. Enhance UI components to display pupil slots and item counts in game screens and map editors. Revise localization strings for improved user guidance. Update tests to validate new functionalities and ensure robustness in handling room and item data.

src/HSchool.Content/MapLayout.cs

@@ -63,6 +63,12 @@ public sealed class SlotFill
     public required string Key { get; init; }
 
     public required string Thing { get; init; }
+
+    /// <summary>
+    /// How many of <see cref="Thing"/> occupy this slot. Missing or non-positive JSON is 1, so
+    /// older maps without a count still round-trip.
+    /// </summary>
+    public int Count { get; init; } = 1;
 }
 
 public sealed class MapLink