refactor: simplify global command path resolution

[xierenyuan]

fix claude code 路径兼容错误

[augmentcode]

🤖 Augment PR Summary

Summary: Adjusts global “.claude” slash-command discovery to resolve under the user home directory (via dirname(globalConfigDir)) instead of one level above it.

Why: Fixes a path compatibility bug where the previous join could incorrectly point to /.claude/commands (filesystem root) rather than ~/.claude/commands.

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[augmentcode]

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[sorrycc]

搜下 globalClaude，skill 和 rule 那看下是否需要一起调整了。

[xierenyuan]

搜下 globalClaude，skill 和 rule 那看下是否需要一起调整了。

done