fix: remove the kernel process and add a shell process (still not working tho)

src/memory/memory.c

@@ -13,7 +13,7 @@ struct frame_zone *head;
 
 void switch_pd(uint32_t *pd, uint32_t *cr3)
 {
-	// current_pd = pd;
+	current_pd = pd;
 	asm volatile("mov %0, %%cr3" ::"r"(cr3));
 }