lots done

src/Roboto.Core/WalkabilitySnapshot.cs

@@ -0,0 +1,15 @@
+namespace Roboto.Core;
+
+public record WalkabilitySnapshot
+{
+    public int Width { get; init; }
+    public int Height { get; init; }
+    public byte[] Data { get; init; } = [];
+
+    public bool IsWalkable(int x, int y)
+    {
+        if (x < 0 || x >= Width || y < 0 || y >= Height)
+            return false;
+        return Data[y * Width + x] != 0;
+    }
+}