fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/stringify-entities/lib/util/to-decimal.d.ts

@@ -0,0 +1,9 @@
+/**
+ * Configurable ways to encode characters as decimal references.
+ *
+ * @param {number} code
+ * @param {number} next
+ * @param {boolean|undefined} omit
+ * @returns {string}
+ */
+export function toDecimal(code: number, next: number, omit: boolean | undefined): string;