add custom chess engine

native/chess_engine/src/perft.h

@@ -0,0 +1,14 @@
+// Perft: counts the leaf nodes of the legal move tree to a given depth.
+// The standard correctness test for move generation + make/unmake.
+#ifndef CHESS_PERFT_H
+#define CHESS_PERFT_H
+
+#include "position.h"
+
+namespace chess {
+
+uint64_t perft(Position& pos, int depth);
+
+} // namespace chess
+
+#endif // CHESS_PERFT_H