feat: add nginx config generator

[RexWzh]

Summary

• add a new chattool nginx command with a small config-oriented template set for common nginx generation flows
• make the nginx workflow interactive by default on missing required inputs, prompting for only the necessary template fields
• align chattool pypi init and chattool setup workspace with the current CLI interaction rules, including repo credential reuse and direct token input defaults

Testing

• python -m pytest -q "mock-cli-tests/nginx/test_chattool_nginx_dispatch_basic.py" "mock-cli-tests/pypi/test_chattool_pypi_init_interactive.py" "cli-tests/nginx/test_chattool_nginx_render_basic.py" "cli-tests/pypi/test_chattool_pypi_basic.py"
• python -m pytest -q "mock-cli-tests/setup/test_chattool_setup_workspace_mock_basic.py"

[github-actions]

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