feat: derive atlas tile size from loaded texture dimensions

Core/Game.cs

@@ -44,7 +44,7 @@ public sealed class Game : GameWindow
             this._world.SetChunk(new Vector3i(x, 0, z), this.BuildChunk());
         }
 
-        ChunkMesher mesher = new();
+        ChunkMesher mesher = new(this._texture.Width, this._texture.Height);
         foreach ((Vector3i pos, Chunk chunk) in this._world)
         {
             Vector3i origin = pos *  Chunk.Size;