Automations don't work with Jujutsu VCS changes

### Short summary

Automations fail to run because my repo uses JJ for version control which puts the underlying Git repo in a Detached HEAD state

### Affected version or release

v1.0.6

### Installation context

_No response_

### What happened?

When automations get triggered, the following error message is surfaced:
`Branch workflow cannot start from a detached HEAD. Check out the branch you want this workflow to run on, then run it again.`

### Steps to reproduce

1. Initialize JJ in a Git repo
2. Create a new JJ change
3. Create an automation on that repo

### Expected behavior

The automation is able to run successfully

### Additional context

_No response_

按照列出的步骤重现该问题：在 Git 仓库中初始化 Jujutsu，创建一个 JJ change，并触发自动化。从 detached-HEAD 错误路径开始，验证自动化启动如何处理由 JJ 管理的仓库。完成的标准是自动化成功运行，而不是报告 workflow 无法从 detached HEAD 启动。

由索引模型根据 Issue 内容生成。