Translation & Fixes: Added Chinese README and corrected links

[xiaoditx]

Hi, this PR introduces Chinese translations for the README and fixes some broken links in the original document.

What's included:

• Added three variants of Chinese translation: Simplified Chinese, Traditional Chinese (Taiwan), and Traditional Chinese (Hong Kong/Macau).
• Fixed a number of incorrect links in the original README (though I'm not entirely sure if all corrections are perfect).
• Added a link to the Chinese version in introduction.md. Since the current translation only covers about 50% of the full English website, I've temporarily pointed this link to my personal site. This allows users to access the most up-to-date version and provides a foundation for future, more comprehensive localization.

Thank you for considering this contribution!

[ArthurSonzogni]

Thank you very much @xiaoditx !

• Broken links I fixed the generation here
• I've temporarily pointed this link to my personal site => That's okay for me. Especially if this avoids me to maintain it.

I am okay to merge the part adding the external link!

Long term, I believe I would like something with low maintenance cost, mostly correct, improvable, that would scale to multiple languages, not increasing the repository size. Here is an idea:

• In an orphan branch and/or an external repository:
• A python script would pull:
  • The content of the orphan branch
  • The content of origin/<latest_release> .
• A gemini-cli prompt would be asked to translate the Doxygen comments and markdown from origin/<latest_release>. As much as possible, it should copy the previous translatiosn from the orphan branch.
• Generate the doc and push it to the orphan branch.
• When FTXUI generates the doc, it can cherry-pick the content of the orphan branchs.

What do you think about this ideas?

[ArthurSonzogni]

I tried the AI idea:
https://github.com/ArthurSonzogni/ftxui-translations/tree/zh-CN

It is not complete, and costed me ~35€ already, which is way too much. However calling the script to update translation would be scalable to multiple language and maintainable.
I am going to investigate how to scale down the cost and let you review the python script driving AI to achieve this.

[xiaoditx]

I've taken a close look at that AI translation repository, and the overall performance is indeed quite good. However, as you mentioned, the pricing is on the higher side—thirty-five euros, based on the cost of living in China, is roughly equivalent to 4–6 days of daily food expenses for a family of three. I recently looked into Youdao's translation API, which is officially priced at 48 RMB per million characters. It seems much more cost-effective, though I'm not yet sure if it fully meets our functional requirements.

Additionally, regarding the quality of AI translations, I noticed some inaccuracies in certain parts of the translated documentation. It might be a good idea to retain human-translated versions for these specific segments and implement a protection mechanism to prevent them from being automatically overwritten by AI translations, unless the corresponding source content is updated.

By the way, shouldn’t we add a link to the Chinese version of the repository in the README now?