fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/stringify-entities/lib/util/format-basic.js

@@ -0,0 +1,9 @@
+/**
+ * The smallest way to encode a character.
+ *
+ * @param {number} code
+ * @returns {string}
+ */
+export function formatBasic(code) {
+  return '&#x' + code.toString(16).toUpperCase() + ';'
+}