Patch refactor scm and textui (#289)

* 重构屏幕管理器和textui框架

* 切换字体为spleen，并增加对字体的抽象

* 修正文档

---------

Co-authored-by: longjin <longjin@RinGoTek.cn>

user/libs/libc/src/unistd.c

@@ -155,6 +155,7 @@ int execv(const char *path, char *const argv[])
         errno = -ENOENT;
         return -1;
     }
+
     int retval = syscall_invoke(SYS_EXECVE, (uint64_t)path, (uint64_t)argv, 0, 0, 0, 0, 0, 0);
     if (retval != 0)
         return -1;