Fix: Invalid script entry point in setup.py

[newwlfz]

Problem Description

Fix the invalid script entry point configuration in setup.py that caused installation issues when using pip.

Changes Made

• Fixed console_scripts entry point in setup.py to correctly point to pynetinstall.__main__:main
• Encapsulated main execution logic into main() function in pynetinstall/__main__.py
• Updated README.md Usage section to reflect correct command line usage

Impact

• Resolves "ERROR: Invalid script entry point..." installation error
• Users can now properly run pyNetinstall via pynetinstall command after pip installation
• Maintains backward compatibility with existing usage patterns

问题描述

修复setup.py中无效的脚本入口点配置，解决pip安装时的错误。

修改内容

• 修复setup.py中的console_scripts入口点，指向pynetinstall.main:main
• 在pynetinstall/main.py中添加main()函数封装执行逻辑
• 更新README.md中的Usage部分，反映正确的命令行用法

影响范围

• 解决"ERROR: Invalid script entry point..."安装错误
• 用户安装后可通过pynetinstall命令直接运行
• 保持向后兼容性