feat: 静态资源与前端 Markdown、浏览量、Gitea 同步内容

- 将 Markdown/KaTeX/高亮/Mermaid 移至 public 与 CDN，减小 Worker 体积
- 文章列表：标题、简介、时间与浏览量；访问文章时递增 view_count
- 新增 migrations/0003 与 blog 路由等配置
- 加入 public 资源与站点图标

Made-with: Cursor

wrangler.toml

@@ -2,6 +2,13 @@ name = "sproutblog"
 main = "worker.js"
 compatibility_date = "2026-04-13"
 
+routes = [
+  { pattern = "blog.smyhub.com/*", zone_name = "smyhub.com" }
+]
+
+[assets]
+directory = "./public/"
+
 [vars]
 ADMIN_PASSWORD = "shumengya520"