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.Protocol/Messages.cs

@@ -44,15 +44,21 @@ public readonly record struct ServerSchoolGoneMessage(int SchoolId);
 /// <summary>
 /// Tree node in a map snapshot. Kind is <c>0</c> territory, <c>1</c> building, <c>2</c> floor, <c>3</c> room.
 /// <paramref name="ParentId"/> is empty for the yard.
+/// <paramref name="PupilSlots"/> is how many pupils can take a lesson here — summed from things
+/// on the server, not by the client.
 /// </summary>
 public sealed record MapSnapshotNode(
     byte Kind,
     string Id,
     string ParentId,
     string Name,
-    IReadOnlyList<string> Items,
+    ushort PupilSlots,
+    IReadOnlyList<MapSnapshotItem> Items,
     IReadOnlyList<string> Positions);
 
+/// <summary>One stacked thing in a room. <paramref name="Count"/> is 1–255.</summary>
+public sealed record MapSnapshotItem(string Name, byte Count);
+
 /// <summary>
 /// One school's map, labelled in the Hello locale. Sent once when that school is opened, not every tick.
 /// People and in-place activities are omitted — the client keeps those sections empty.