fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/widest-line/index.d.ts

@@ -0,0 +1,12 @@
+/**
+Get the visual width of the widest line in a string - the number of columns required to display it.
+
+@example
+```
+import widestLine from 'widest-line';
+
+widestLine('古\n\u001B[1m@\u001B[22m');
+//=> 2
+```
+*/
+export default function widestLine(string: string): number;