docs: add JSDoc headers to all externally exported store functions

src/store/companyuser/add.js

@@ -1,5 +1,16 @@
 import { ADD } from '../../sql/companyuser.js';
 
+/**
+ * Adds a company user linking a company to a Google auth account.
+ *
+ * @param {object} pool - The mssql connection pool.
+ * @returns {Function} An async function that creates the company user link.
+ *
+ * @example
+ * const fn = add(pool);
+ * const id = await fn(1, 42);
+ * // => 7
+ */
 export default function add(pool) {
   return async (companyId, googleAuthId) => {
     const result = await pool