core: change types from uint32_t to u32 (e.g)

headers/alloc.h

@@ -1,9 +1,7 @@
 #pragma once
 
-// boolean types
+#include "types.h"
 #include <stdbool.h>
-
-// size_t, already in libft.h but for readability
 #include <stddef.h>
 
 // Remove this and replace it with <assert.h> header