chore: 升级 Astro 5.16.5 → 7.3.3

依赖
- astro 5 → 7.3.3，@astrojs/{mdx,react,rss,sitemap,check}、astro-expressive-code
  与 @swup/astro 同步升到最新
- 新增 @astrojs/markdown-remark（Astro 7 默认改用 Sätteri 处理器，
  本项目依赖大量 remark/rehype 插件，故显式固定回 unified 管线）

内容集合迁移到 Content Layer API（Astro 6 已移除旧 API）
- src/content/config.ts → src/content.config.ts，三个集合改用 glob() loader
- z 改从 astro/zod 导入
- 所有 entry.slug → entry.id；entry.render() → render(entry)

Astro 7 兼容
- 修复 bookshelf-content.astro 里多行 {/* */} 注释导致的 Rust 编译器
  "Unterminated regular expression"
- 删除该文件里一处多余的 </div>（旧 Go 编译器会静默纠正，新编译器不会）
- global.css: @import "tailwindcss" → "tailwindcss/index.css"
  （Vite 8 不再解析裸包名的 style 条件）
- astro.config.mjs 显式设置 compressHTML: true，保持 v6 的空白处理行为

验证：构建 41 页通过；与线上（Astro 5 构建）对比 39 个 URL 无一丢失，
仅新增新文章 DIY-computer 的 2 个 URL；逐页渲染文本与线上一致；
pnpm build 与 dev server 均正常。

package.json

@@ -14,14 +14,15 @@
     "reading": "node scripts/fetch-reading.mjs"
   },
   "dependencies": {
-    "@astrojs/mdx": "^5.0.6",
-    "@astrojs/react": "^4.4.2",
-    "@astrojs/rss": "^4.0.12",
-    "@astrojs/sitemap": "^3.5.1",
+    "@astrojs/markdown-remark": "^7.3.1",
+    "@astrojs/mdx": "^8.0.1",
+    "@astrojs/react": "^6.0.6",
+    "@astrojs/rss": "^4.0.19",
+    "@astrojs/sitemap": "^3.7.4",
     "@aws-sdk/client-s3": "^3.1037.0",
-    "@expressive-code/core": "^0.41.5",
-    "@expressive-code/plugin-collapsible-sections": "^0.41.5",
-    "@expressive-code/plugin-line-numbers": "^0.41.5",
+    "@expressive-code/core": "^0.44.2",
+    "@expressive-code/plugin-collapsible-sections": "^0.44.2",
+    "@expressive-code/plugin-line-numbers": "^0.44.2",
     "@hookform/resolvers": "^3.10.0",
     "@radix-ui/react-accordion": "1.2.2",
     "@radix-ui/react-alert-dialog": "1.1.4",
@@ -50,9 +51,9 @@
     "@radix-ui/react-toggle": "1.1.1",
     "@radix-ui/react-toggle-group": "1.1.1",
     "@radix-ui/react-tooltip": "1.1.6",
-    "@swup/astro": "^1.7.0",
+    "@swup/astro": "^1.8.0",
     "@tabler/icons-react": "^3.40.0",
-    "astro-expressive-code": "^0.41.5",
+    "astro-expressive-code": "^0.44.2",
     "autoprefixer": "^10.4.20",
     "bcryptjs": "^3.0.2",
     "class-variance-authority": "^0.7.1",
@@ -102,7 +103,7 @@
     "@types/react": "^19",
     "@types/react-dom": "^19",
     "@types/sanitize-html": "^2.16.0",
-    "astro": "^5.16.5",
+    "astro": "^7.3.3",
     "postcss": "^8.5",
     "tailwindcss": "^4.1.9",
     "tw-animate-css": "1.3.3",