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/SchoolWorker.cs

@@ -48,7 +48,7 @@ internal sealed class SchoolWorker
     private DefCatalog? _catalogSnapshot;
     private Timetable? _timetableSnapshot;
     private MapLayout? _mapSnapshot;
-    private OccupancyKey _occupancyKey;
+    private int _presenceAge;
     private School? _school;
     private Task? _run;
     private bool _persistOnStop = true;
@@ -308,7 +308,7 @@ internal sealed class SchoolWorker
                 {
                     PublishSnapshot();
                     BroadcastClock();
-                    MaybeBroadcastOccupancy(school);
+                    MaybeBroadcastPresence(school);
                 }
 
                 FlushSettings();
@@ -381,6 +381,7 @@ internal sealed class SchoolWorker
                         open.Client.OpenSchoolId = _id;
                         SendMapSnapshot(open.Client, school);
                         BroadcastClockTo(open.Client, school);
+                        SendPresence(open.Client, school);
                         break;
 
                     case WorkerCommand.Close close:
@@ -402,6 +403,10 @@ internal sealed class SchoolWorker
                         dirty = true;
                         break;
 
+                    case WorkerCommand.SkipEmpty:
+                        ApplySkip(school);
+                        break;
+
                     case WorkerCommand.GetPerson getPerson:
                         var card = PersonCardReader.Read(school, getPerson.PersonId, getPerson.Locale);
                         getPerson.Result.TrySetResult(
@@ -613,7 +618,6 @@ internal sealed class SchoolWorker
                     PersistTimetable(school);
                 }
 
-                RememberOccupancy(school);
                 return;
             }
         }
@@ -770,11 +774,7 @@ internal sealed class SchoolWorker
         PublishSnapshot();
         if (broadcast)
         {
-            MaybeBroadcastOccupancy(school, force: true);
-        }
-        else
-        {
-            RememberOccupancy(school);
+            BroadcastPresence();
         }
     }
 
@@ -799,35 +799,41 @@ internal sealed class SchoolWorker
         }
     }
 
-    private void RememberOccupancy(School school)
+    private void MaybeBroadcastPresence(School school)
     {
-        if (school.Catalog is not null)
+        _presenceAge++;
+        var interval = Math.Max(1, _options.TickRate / 2);
+        if (_presenceAge < interval)
         {
-            _occupancyKey = TimetableClock.Key(school.Catalog, school.Clock.Time, _options.SchoolWeekDays);
+            return;
         }
+
+        _presenceAge = 0;
+        BroadcastPresence();
     }
 
-    private void MaybeBroadcastOccupancy(School school, bool force = false)
+    private void ApplySkip(School school)
     {
-        if (school.Catalog is null)
+        var result = school.TrySkipEmpty();
+        if (!result.Succeeded)
         {
             return;
         }
 
-        var key = TimetableClock.Key(school.Catalog, school.Clock.Time, _options.SchoolWeekDays);
-        if (!force && key == _occupancyKey)
+        if (result.PeopleChanged)
         {
-            return;
-        }
-
-        _occupancyKey = key;
-        foreach (var client in _clients.All)
-        {
-            if (client.IsReady && client.OpenSchoolId == _id)
+            PersistPeople();
+            if (school.TimetableDirty)
             {
-                SendMapSnapshot(client, school);
+                RebuildTimetable(school);
             }
         }
+
+        PublishSnapshot();
+        Persist();
+        BroadcastClock();
+        BroadcastPresence();
+        _presenceAge = 0;
     }
 
     private bool InstallPeople(School school, DefCatalog catalog, MapLayout map)
@@ -987,8 +993,6 @@ internal sealed class SchoolWorker
                 node.Positions);
         }
 
-        MapOccupancy.Apply(nodes, school, _options.SchoolWeekDays, locale);
-
         // Sized from the message, not from the inbound frame limit: a map the player enlarged in
         // the create editor outgrows 8 KiB somewhere past sixty furnished rooms.
         var message = new ServerMapSnapshotMessage(school.Id, nodes);
@@ -997,15 +1001,44 @@ internal sealed class SchoolWorker
         client.TrySendReliable(frame.AsMemory(0, length));
     }
 
-    private static void BroadcastClockTo(GameClient client, School school)
+    private void BroadcastClockTo(GameClient client, School school)
     {
+        var skip = school.PeekSkipEmpty();
         var frame = new byte[ProtocolCodec.MaxFrameSize];
         var length = ProtocolCodec.WriteClock(frame, new ServerClockMessage(
             school.Id,
             new DateTimeOffset(school.Clock.Time).ToUnixTimeMilliseconds(),
             school.Clock.IsRunning,
-            (byte)school.Clock.SpeedIndex));
+            (byte)school.Clock.SpeedIndex,
+            skip.Allowed,
+            skip.Time is { } target ? new DateTimeOffset(target).ToUnixTimeMilliseconds() : 0));
 
         client.TrySend(frame.AsMemory(0, length));
     }
+
+    private void BroadcastPresence()
+    {
+        var school = _school;
+        if (school is null)
+        {
+            return;
+        }
+
+        foreach (var client in _clients.All)
+        {
+            if (client.IsReady && client.OpenSchoolId == _id)
+            {
+                SendPresence(client, school);
+            }
+        }
+    }
+
+    private void SendPresence(GameClient client, School school)
+    {
+        var locale = ProtocolConstants.CatalogLocale(client.Locale);
+        var message = PresenceFrame.Build(school, _options.SchoolWeekDays, locale);
+        var frame = new byte[ProtocolCodec.PresenceSize(message)];
+        var length = ProtocolCodec.WritePresence(frame, message);
+        client.TrySendReliable(frame.AsMemory(0, length));
+    }
 }