fix: simple multitasking work !!!!

add a stack at every task, and execute task while multitasking switching

headers/task.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "list.h"
+#include "memory.h"
 
 #include <stdint.h>
 
@@ -9,6 +10,8 @@ extern struct task *current_task;
 enum status { ZOMBIE, THREAD, RUN };
 enum owner { OWNER_KERNEL, OWNER_USER };
 
+#define STACK_SIZE PAGE_SIZE * 4
+
 struct task {
 	uint32_t *esp;
 	uint32_t *esp0;