Refactor project structure and update documentation. Replace PixiJS with plain DOM for UI rendering, enhance README with game features, and revise protocol documentation for HTTP API. Remove unused files and streamline client code for better maintainability.

src/HSchool.Server/Game/GameMetrics.cs

@@ -10,16 +10,17 @@ internal sealed class GameMetrics : IDisposable
     private readonly Meter _meter;
     private readonly Counter<long> _ticks;
     private readonly Histogram<double> _tickDuration;
-    private readonly UpDownCounter<long> _connectedPlayers;
-    private readonly Counter<long> _snapshotBytes;
+    private readonly UpDownCounter<long> _connections;
+
+    private int _schools;
 
     public GameMetrics(IMeterFactory meterFactory)
     {
         _meter = meterFactory.Create(MeterName);
         _ticks = _meter.CreateCounter<long>("hschool.game.ticks", "{tick}", "Simulation steps executed.");
         _tickDuration = _meter.CreateHistogram<double>("hschool.game.tick.duration", "ms", "Wall time of one simulation step.");
-        _connectedPlayers = _meter.CreateUpDownCounter<long>("hschool.game.players", "{player}", "Currently connected players.");
-        _snapshotBytes = _meter.CreateCounter<long>("hschool.game.snapshot.bytes", "By", "Snapshot bytes pushed to clients.");
+        _connections = _meter.CreateUpDownCounter<long>("hschool.game.connections", "{connection}", "Open WebSocket connections.");
+        _meter.CreateObservableGauge("hschool.game.schools", () => Volatile.Read(ref _schools), "{school}", "Schools that currently exist.");
     }
 
     public void RecordTick(double durationMs)
@@ -28,11 +29,11 @@ internal sealed class GameMetrics : IDisposable
         _tickDuration.Record(durationMs);
     }
 
-    public void PlayerJoined() => _connectedPlayers.Add(1);
+    public void ClientConnected() => _connections.Add(1);
 
-    public void PlayerLeft() => _connectedPlayers.Add(-1);
+    public void ClientDisconnected() => _connections.Add(-1);
 
-    public void SnapshotSent(int bytes, int recipients) => _snapshotBytes.Add((long)bytes * recipients);
+    public void SchoolsChanged(int count) => Volatile.Write(ref _schools, count);
 
     public void Dispose() => _meter.Dispose();
 }