feat: metrics test.

Game/Game/GameServiceSource.cs

@@ -1,10 +1,12 @@
 using Godot;
 using GodotHostTest.AetherBind;
 using GodotHostTest.Game.Level;
+using GodotHostTest.Game.Metrics;
 using GodotHostTest.Game.Score;
 using GodotHostTest.Game.Target;
 using GodotHostTest.Interfaces;
 using Microsoft.Extensions.DependencyInjection;
+using OwofGames.GodotHost;
 using OwofGames.GodotHost.Observability;
 using OwofGames.GodotLume;
 
@@ -23,12 +25,16 @@ public partial class GameServiceSource : RootServiceSource
             // current level / level data management
             .AddInstance<ILevelDataProvider, LevelsData>(_levelsData)
             .AddSingleton<ICurrentLevel, CurrentLevel>()
+            // metrics
+            .AddSingleton<IHostLifetime, MetricsHandler>()
             // level scope services
             .AddLevelServices();
     }
 
     protected override void ConfigureServices(IServiceCollection serviceCollection)
     {
-        serviceCollection.AddObservability(builder => builder.AddGrpcExporter("http://localhost:4317"));
+        serviceCollection.AddObservability(builder => builder
+            .AddGrpcExporter("http://localhost:4317")
+            .AddMeterName(MetricsHandler.MeterName));
     }
 }