fix: Add nixpacks configuration for Astro deployment

dealplustech-astro/node_modules/mdast-util-gfm-footnote/index.d.ts

@@ -0,0 +1,34 @@
+export {gfmFootnoteFromMarkdown, gfmFootnoteToMarkdown} from './lib/index.js'
+
+export interface ToMarkdownOptions {
+  // To do: next major: change default.
+  /**
+   * Use a blank line for the first line of footnote definitions
+   * (`boolean`, default: `false`).
+   */
+  firstLineBlank?: boolean | null | undefined
+}
+
+declare module 'mdast-util-to-markdown' {
+  interface ConstructNameMap {
+    /**
+     * Footnote definition.
+     *
+     * ```markdown
+     * > | [^a]: B.
+     *     ^^^^^^^^
+     * ```
+     */
+    footnoteDefinition: 'footnoteDefinition'
+
+    /**
+     * Footnote reference.
+     *
+     * ```markdown
+     * > | A[^b].
+     *      ^^^^
+     * ```
+     */
+    footnoteReference: 'footnoteReference'
+  }
+}