fix: 首页改推 OpenClaw，修复 xcodeclaw 页面 showcase 渲染问题

- 首页 hero 按钮和 feature 卡片从 Cherry Studio 改为 OpenClaw（飞书优先）
- Cherry Studio 移入侧边栏「快速开始」分组，移除空的「参考」分组
- 修复 xcodeclaw.md 学术场景 showcase 区块因空行+缩进被解析为代码块的问题
- CTA 背景渐变改用主题变量，适配深色模式

docs/.vitepress/config.ts

@@ -24,6 +24,7 @@ export default defineConfig({
           { text: "Claude Code", link: "/guide/claude-code" },
           { text: "Gemini CLI", link: "/guide/gemini-cli" },
           { text: "Codex", link: "/guide/codex" },
+          { text: "Cherry Studio 配置", link: "/cherry-studio-nanobana" },
         ],
       },
       {
@@ -33,12 +34,6 @@ export default defineConfig({
           { text: "飞书机器人配置", link: "/guide/feishu-bot" },
         ],
       },
-      {
-        text: "参考",
-        items: [
-          { text: "Cherry Studio 配置", link: "/cherry-studio-nanobana" },
-        ],
-      },
     ],
 
     socialLinks: [