fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/nlcst-to-string/lib/index.d.ts

@@ -0,0 +1,13 @@
+/**
+ * Get the text content of a node or list of nodes.
+ *
+ * Prefers the node’s plain-text fields, otherwise serializes its children, and
+ * if the given value is an array, serialize the nodes in it.
+ *
+ * @param {Array<Nodes> | Nodes} value
+ *   Node or list of nodes to serialize.
+ * @returns {string}
+ *   Result.
+ */
+export function toString(value: Array<Nodes> | Nodes): string;
+export type Nodes = import('nlcst').Nodes;