Add Trendshift badge to README files

[Copilot]

Plan: Add Trendshift badge to README files

• Add Trendshift badge to README.md (English)
• Add Trendshift badge to README.zh-CN.md (Chinese)
• Center the badge using <p align="center"> tag
• Position badge in the badge area above the description
• Verify the changes

Original prompt

在 readme 中加入以下内容。

注意事项：

1. 中英文的 readme 都需要修改
2. 加在「AntV X6 is a graph editing engine based on HTML and SVG, providing low-cost customization capabilities and out-of-the-box built-in extensions that make it easy to quickly build applications such as DAG diagrams, ER diagrams, flowcharts, lineage graphs, and more. We hope developers can use X6 to rapidly build various graph editing applications they need, making process relationship data controllable, interactive, and visualized.」上面一行

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