Case Studies Default to Chinese Due to Markdown Content

**Describe the bug**

Several case study pages on the KubeEdge website default to Chinese because their Markdown content is written in Chinese. When users try to switch to English via the language dropdown, they are redirected back to the previous page instead of viewing an English version of the case study. This leads to a poor user experience, as non-Chinese speakers must rely on external translation tools to understand the content.

**Affected Pages:**

[CMCC Panzhou Panji Platform](https://kubeedge.io/zh/case-studies/cmcc/)
[SF Tech](https://kubeedge.io/zh/case-studies/sf-tech/)
[ZCITC](https://kubeedge.io/zh/case-studies/zcitc/)
[CTYun](https://kubeedge.io/case-studies/ctyun/)
[CAII](https://kubeedge.io/zh/case-studies/caii/)
[Kuiper](https://kubeedge.io/zh/case-studies/kuiper/)

**To Reproduce**
Steps to reproduce the behavior:

1. Go to KubeEdge Case Studies.
2. Click on any of the affected case study links.
3. The page provides a link to the case study (e.g., https://kubeedge.io/zh/case-studies/cmcc/). Click on it.
4. The case study opens in Chinese.
5. Click on the language dropdown and select "English."
6. Instead of displaying the case study in English, you are redirected back to the previous page where the link was provided.

**Expected behavior**
Case study content should be available in English when users switch the language.
If an English version is not available, the site should provide an appropriate fallback instead of redirecting to the previous page.

**Screenshots**

**The case study opens in Chinese. Click on the language dropdown and select "English."**


**Instead of displaying the case study in English, you are redirected back to the previous page where the link was provided.**


**Proposed Solution**
The root cause of this issue is that the Markdown files for these case studies are written in Chinese. To improve accessibility and user experience, I propose translating these Markdown files into English so that English-speaking users can access the content seamlessly.

**Additional context**
Translating the case study Markdown content into English would make these pages more accessible to a global audience and align with the multilingual support expectations of the website.