fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/is-docker/index.d.ts

@@ -0,0 +1,13 @@
+/**
+Check if the process is running inside a Docker container.
+
+@example
+```
+import isDocker from 'is-docker';
+
+if (isDocker()) {
+	console.log('Running inside a Docker container');
+}
+```
+*/
+export default function isDocker(): boolean;