fix: add ssr adapter for vercel

astro.config.mjs

@@ -2,8 +2,11 @@ import { defineConfig } from 'astro/config';
 import tailwind from "@astrojs/tailwind";
 import preact from "@astrojs/preact";
 
+import vercel from "@astrojs/vercel/serverless";
+
 // https://astro.build/config
 export default defineConfig({
   integrations: [tailwind(), preact()],
-  output: 'server'
-});
+  output: 'server',
+  adapter: vercel()
+});

package.json

@@ -5,6 +5,7 @@
     "@astrojs/check": "^0.9.2",
     "@astrojs/preact": "^3.5.1",
     "@astrojs/tailwind": "^5.1.0",
+    "@astrojs/vercel": "^7.7.2",
     "@nanostores/preact": "^0.5.2",
     "astro": "^4.14.2",
     "nanostores": "^0.11.2",