docs: add JSDoc headers to all externally exported store functions

src/store/lang/list.js

@@ -1,5 +1,16 @@
 import { LIST } from '../../sql/language.js';
 
+/**
+ * Lists all languages.
+ *
+ * @param {object} pool - The mssql connection pool.
+ * @returns {Function} An async function that lists languages.
+ *
+ * @example
+ * const fn = list(pool);
+ * const languages = await fn();
+ * // => [{ id, iso639 }]
+ */
 export default function list(pool) {
   return async () => {
     const result = await pool.request().query(LIST);