Bare operations so that this work with jujutsu, etc.

I'm using jujutsu so please provide commands that does not create any branch, checkout any branch, etc.
For comparison, graphite has `--branch` arg for essential commands so it can work with jujutsu.

I'll even question why it isn't designed like this. Like you only need
`gh stack `: Stack `branch1` on top of `branch2`, or if branch2 is missing, it will be the first branch in the stack
`gh submit `: Push a tracked branch to github.

首先检查现有命令的行为，以及 issue 中描述的 jujutsu 和 Graphite 对比。明确哪些操作必须避免创建分支或 checkout，然后说明提议的命令接口，以及缺少第二个分支和提交跟踪分支时的行为。

由索引模型根据 Issue 内容生成。