refactor: port site from Jekyll to Astro

astro.config.mjs

@@ -0,0 +1,12 @@
+import { defineConfig } from "astro/config";
+import tailwindcss from "@tailwindcss/vite";
+import sitemap from "@astrojs/sitemap";
+
+export default defineConfig({
+  site: "https://commonflow.org",
+  outDir: "./docs",
+  integrations: [sitemap()],
+  vite: {
+    plugins: [tailwindcss()],
+  },
+});