docs: add JSDoc headers to all externally exported store functions

src/store/article/addImage.js

@@ -5,6 +5,17 @@ import newFullHash from '../../util/newFullHash.js';
 import request from '../request.js';
 import resolveArticleBySku from './resolveArticleBySku.js';
 
+/**
+ * Adds an image to an article by its SKU, processing it into AVIF variants.
+ *
+ * @param {object} pool - The mssql connection pool.
+ * @returns {Function} An async function that adds an article image.
+ *
+ * @example
+ * const fn = addImage(pool);
+ * const result = await fn(42, 'SKU-1', imageBuffer);
+ * // => { picId, sort, full: { w, h, size }, thumb: { w, h }, fullHash, thumbHash }
+ */
 export default function addImage(pool) {
   const resolve = resolveArticleBySku(pool);