move windowing code into io/win

src/io/win/window.h

@@ -0,0 +1,20 @@
+/* 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. */
+#pragma once
+
+/* Set up the window, enabling OpenGL, and
+ * configuring the settings that are needed.
+ * Returns `0` upon success, otherwise `1`. */
+int window_init(void);
+
+/* Calls the update loop for the window.
+ * This function does not exit until the window does. */
+void window_loop(void);
+
+/* Requests the window to close (gracefully). */
+void window_close(void);
+
+/* Cleans up all resources held by the window.
+ * If the window is still open, it will be terminated. */
+void window_free(void);