* feature: add China image configuration options
* feature: update Python and Poetry mirror configurations to use Tsinghua and Aliyun
* feature: improve Poetry mirror configuration to check for existing sources
* feature: rename setup-china to setup-cn and update pip mirror to Aliyun
* Add MD file
* Modify GitHub download
* Change to Chinese Mainland
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Co-authored-by: yanmuyuan <2216646664@qq.com>