Restructure blogs as Astro monorepo

sites/art/astro.config.mjs

@@ -0,0 +1,22 @@
+// @ts-check
+import { defineConfig } from "astro/config";
+import mdx from "@astrojs/mdx";
+import sitemap from "@astrojs/sitemap";
+
+import react from "@astrojs/react";
+// @ts-ignore - TailwindCSS v4 Vite plugin has type compatibility issues with Astro
+import tailwindcss from "@tailwindcss/vite";
+import { ACTIVE_BLOG_SITE } from "./src/blog-sites.js";
+
+// https://astro.build/config
+export default defineConfig({
+  site: ACTIVE_BLOG_SITE.url,
+  integrations: [mdx(), sitemap(), react()],
+  output: "static",
+  outDir: "dist",
+
+  vite: {
+    // @ts-ignore - Suppress TypeScript error for TailwindCSS v4 plugin compatibility
+    plugins: [tailwindcss()],
+  },
+});