move windowing code into io/win

src/io/win/input.c

@@ -0,0 +1,15 @@
+/* Copyright (c) 2025 Quinn.
+ * This is a file from the project MCA-Selector-Lite and is
+ * licensed under the MIT Licence. See the project's LICENSE file for details. */
+#include "input.h"
+
+#include <GLFW/glfw3.h>
+
+void input_callback(GLFWwindow *win, int key, int scancode, int action, int mods)
+{
+	(void)win, (void)key, (void)scancode, (void)action, (void)mods; // make the compiler shut up as this is fine
+#ifndef NDEBUG
+	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+		glfwSetWindowShouldClose(win, 1);
+#endif
+}