fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/astro/dist/vite-plugin-fileurl/index.d.ts

@@ -0,0 +1,2 @@
+import type { Plugin as VitePlugin } from 'vite';
+export default function vitePluginFileURL(): VitePlugin;

dealplustech-astro/node_modules/astro/dist/vite-plugin-fileurl/index.js

@@ -0,0 +1,15 @@
+function vitePluginFileURL() {
+  return {
+    name: "astro:vite-plugin-file-url",
+    enforce: "pre",
+    resolveId(source, importer) {
+      if (source.startsWith("file://")) {
+        const rest = source.slice(7);
+        return this.resolve(rest, importer);
+      }
+    }
+  };
+}
+export {
+  vitePluginFileURL as default
+};