Chinese (zh) locale does not fully translate blog content, but only headers and navigation

### Description

When switching the website language to **Chinese (zh / 简体中文)** using the language selector, only the **navigation, headings, and some metadata** are translated. The **main blog content, sidebar entries, and section text remain in English**.

This behavior is inconsistent across blog pages and creates a partially localized experience.

### Some Affected Pages or Examples

- https://kmesh.net/zh/blog/kmesh-1.1-release
- https://kmesh.net/zh/blog/ospp_2025_ut_test

### Observed Behavior

- ✅ Header, footer, navigation labels are translated
- ✅ Page metadata (date, reading time) is translated
- ❌ Blog body content remains in English
- ❌ Sidebar blog list items remain in English
- ❌ Table of contents entries remain in English

### Expected Behavior

When a user selects **Chinese (zh)**:
- Blog pages should either:
- Fully display Chinese-translated content, **or**
- Clearly fall back to English consistently (not mixed)

### Screenshots

_Attached screenshots show multiple sections where content is not translated despite zh locale being active._

### Possible Cause

This may be due to:
- Missing Chinese (`zh`) markdown/MDX files for blog posts
- i18n configuration only applied to UI components, not content pages
- Incomplete localization pipeline for blog content

### Environment

- Browser: Chrome / Safari
- OS: macOS
- Locale selected: 简体中文 (zh)