Update wire protocol to version 7 and enhance presence management features

- Bumped the wire protocol version to 7, reflecting significant changes in the communication structure.
- Introduced a new presence message type for real-time occupancy updates, including node activity and individual presence states.
- Updated the API to include a directory endpoint for fetching short id→name mappings, improving client-side name resolution.
- Revised the map snapshot structure to be static, with people and current lessons now handled through the presence stream.
- Enhanced client-side handling of presence updates, including UI adjustments to display live occupancy and activity.
- Updated documentation to reflect the new protocol features and changes in presence management.
- Added tests to validate the new presence functionalities and ensure robust handling of real-time data.

src/HSchool.Server/Game/WorkerCommand.cs

@@ -18,6 +18,8 @@ internal abstract record WorkerCommand
 
     internal sealed record SetSpeed(byte SpeedIndex) : WorkerCommand;
 
+    internal sealed record SkipEmpty : WorkerCommand;
+
     internal sealed record GetPerson(
         string PersonId,
         string Locale,