Git hook messages aren't displayed

The stack CLI suppresses git hook output, which is confusing when the hooks are slow and frustrating when the hooks fail. For example, a `gh stack push` that fails because of a hook just outputs

```
❯ gh stack push
Skipping 1 merged branch
Pushing 2 branches to origin...
✗ failed to push: failed to run git: error: failed to push some refs to 'github.com:...'
```

首先使用 `gh stack push` 和一个运行缓慢或失败的 Git hook 重现该问题，然后跟踪 stack CLI 如何运行 Git 命令以及如何处理这些命令的输出。当命令执行期间能够看到 hook 消息，并且 hook 失败时仍保留有用的输出，同时继续报告 push 失败时，即视为完成。

由索引模型根据 Issue 内容生成。