feat: 改进设置页面UI和国际化支持 / Improve settings pages UI and i18n support

- 添加 rehype-raw 依赖以支持在 markdown 中渲染 HTML
  Add rehype-raw dependency to support HTML rendering in markdown

- 重构 memory-settings-page，提取 formatMemorySection 函数减少重复代码
  Refactor memory-settings-page by extracting formatMemorySection function to reduce code duplication

- 改进空状态显示，使用 HTML span 标签替代 markdown 斜体，提供更好的样式控制
  Improve empty state display by using HTML span tags instead of markdown italics for better style control

- 为 skill-settings-page 添加完整的国际化支持，替换硬编码的英文文本
  Add complete i18n support for skill-settings-page, replacing hardcoded English text

- 更新国际化文件，添加技能设置页面的空状态文本（中英文）
  Update i18n files with empty state text for skill settings page (both Chinese and English)

- 在 streamdown 插件配置中添加 rehypeRaw 以支持 HTML 渲染
  Add rehypeRaw to streamdown plugins configuration to support HTML rendering

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/package.json

@@ -73,6 +73,7 @@
     "react-dom": "^19.0.0",
     "react-resizable-panels": "^4.4.1",
     "rehype-katex": "^7.0.1",
+    "rehype-raw": "^7.0.0",
     "remark-gfm": "^4.0.1",
     "remark-math": "^6.0.0",
     "shiki": "3.15.0",