fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/is-inside-container/index.d.ts

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