feat: establish the bounded production architecture

include/application.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <stdbool.h>
+
+#include "command_queue.h"
+
+/* The application task is the sole owner of game_state_t mutations. */
+typedef struct { command_queue_t command_queue; game_state_t state; } application_t;
+
+bool application_enqueue(application_t *application, const app_command_t *command);
+bool application_take_next_command(application_t *application, app_command_t *command);