fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/retext/index.d.ts

@@ -0,0 +1,10 @@
+/// <reference types="retext-latin" />
+
+import type {Root} from 'nlcst'
+import type {Processor} from 'unified'
+
+/**
+ * Create a new unified processor that already uses `retext-latin` and
+ * `retext-stringify`.
+ */
+export const retext: Processor<Root, undefined, undefined, Root, string>