Add Astro server configuration files and dependencies

astro/server/astro.config.mjs

@@ -0,0 +1,11 @@
+import { defineConfig } from 'astro/config';
+
+import node from "@astrojs/node";
+
+// https://astro.build/config
+export default defineConfig({
+  output: 'server',
+  adapter: node({
+    mode: "standalone"
+  })
+});