Unable to rename branch in plan mode

### Short summary

Plan mode fails to rename the worktree branch and this blocks plan.md from being created

### Affected version or release

v1.1.14

### Installation context

Windows

### What happened?

In plan mode, the session fails to rename the branch name as it reports the branch name tool is unavailable. This leads to the plan not being created until forced to by yet another prompt.

### Steps to reproduce

1. Start session in repo worktree in plan mode
2. Prompt for a task (I used GPT-5.6 Sol Medium reasoning 400k)
3. Notice how it fails to rename branch and therefore won't make changes in the repo workspace
4. Ask it to create the plan anyway
5. Plan created

### Expected behavior

_No response_

### Additional context

首先，在 repository worktree 中使用 plan mode 复现 Windows v1.1.14 上的故障。跟踪 plan mode 分支重命名和 branch-name 工具可用性的流程，然后验证分支已重命名，并且 plan.md 已在没有额外 prompt 的情况下创建。

由索引模型根据 Issue 内容生成。