feat: add Chunk as a dense 16-cubed id array

World/Chunk.cs

@@ -0,0 +1,19 @@
+namespace VoxelEngine.World;
+
+public sealed class Chunk
+{
+    public const int Size = 16;
+
+    private readonly ushort[] _ids = new ushort[Size * Size * Size];
+
+    public ushort this[int x, int y, int z]
+    {
+        get => _ids[Index(x, y, z)];
+        set => _ids[Index(x, y, z)] = value;
+    }
+
+    public static bool InBounds(int x, int y, int z) =>
+        x >= 0 && x < Size && y >= 0 && y < Size && z >= 0 && z < Size;
+
+    private static int Index(int x, int y, int z) => (x * Size + y) * Size + z;
+}