fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/crossws/dist/adapters/sse.d.ts

@@ -0,0 +1,13 @@
+import { Adapter, AdapterInstance, AdapterOptions } from '../index.js';
+import '../shared/crossws.BQXMA5bH.js';
+
+interface SSEAdapter extends AdapterInstance {
+    fetch(req: Request): Promise<Response>;
+}
+interface SSEOptions extends AdapterOptions {
+    bidir?: boolean;
+}
+declare const sseAdapter: Adapter<SSEAdapter, SSEOptions>;
+
+export { sseAdapter as default };
+export type { SSEAdapter, SSEOptions };