feat: refine setup, skill, and GitHub CLI flows

[RexWzh]

Summary

• reuse chatenv Feishu defaults during chattool cc init -i, shorten the skills config prompt, and align skill config resolution with chatenv
• bundle nvm.sh for chattool setup nodejs, fix the chatskills alias target, and rename the skill CLI package to src/chattool/skill/
• add chattool gh pr-check, refresh the GitHub skill guidance, move scratch or preview outputs outside the repository by default, and shift practice-make-perfact into an explicit post-task normalization phase that chains into chattool-dev-review

Testing

• python3 -m pytest -q tests/tools/github/test_cli.py tests/tools/pypi/test_cli.py
• python3 -m pytest -q tests/ -m 'not dns and not lark'
• python3 -m chattool.client.main gh --help
• python3 -m chattool.client.main gh pr-check --help
• python -m chattool.client.main skill --help
• python -m chattool.skill.cli --help

[github-actions]

Preview available at: https://chattool.wzhecnu.cn/dev/