Implement deterministic simulation spine

src/SideScrollerGame.Sim/Runtime/PlayerSnapshot.cs

@@ -0,0 +1,24 @@
+using System.Diagnostics.CodeAnalysis;
+using SideScrollerGame.Sim.Math;
+
+namespace SideScrollerGame.Sim.Runtime;
+
+[ExcludeFromCodeCoverage]
+public sealed record PlayerSnapshot
+{
+    public PlayerSnapshot(PlayerId playerId, FixPointVector2 position, sbyte moveAxisX, sbyte moveAxisY)
+    {
+        PlayerId = playerId;
+        Position = position;
+        MoveAxisX = moveAxisX;
+        MoveAxisY = moveAxisY;
+    }
+
+    public PlayerId PlayerId { get; init; }
+
+    public FixPointVector2 Position { get; init; }
+
+    public sbyte MoveAxisX { get; init; }
+
+    public sbyte MoveAxisY { get; init; }
+}