Setting to change the "New worktree" behavior for all sessions

It is very annoying that sometimes I just start a new session and it takes minutes to start because it is creating a new worktree. There should be a global setting to change the default to local and then I'll pick when I want a new worktree.

该 issue 没有指明文件、测试或入口点。首先定位 session 创建逻辑和现有的 worktree 行为，然后找到 session 默认值的存储或应用位置。当一个全局设置使新 session 默认使用本地工作，同时仍允许用户在需要时选择新的 worktree 时，即视为完成。

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