docs: add JSDoc headers to all externally exported store functions

src/store/pic/getImageByHash.js

@@ -1,6 +1,17 @@
 import { GET_FULL_BY_HASH } from '../../sql/pic.js';
 import resolvePicAccess from './resolvePicAccess.js';
 
+/**
+ * Returns the full-size image (AVIF) for a given hash.
+ *
+ * @param {object} pool - The mssql connection pool.
+ * @returns {Function} An async function that fetches a full image by hash.
+ *
+ * @example
+ * const fn = getImageByHash(pool);
+ * const image = await fn(42, 'abc123');
+ * // => { buffer, w, h, size, contentType: 'image/avif' }
+ */
 export default function getImageByHash(pool) {
   const authorize = resolvePicAccess(pool);
 

src/store/pic/getThumbByHash.js

@@ -1,6 +1,17 @@
 import { GET_THUMB_BY_HASH } from '../../sql/pic.js';
 import resolvePicAccess from './resolvePicAccess.js';
 
+/**
+ * Returns the thumbnail image (AVIF) for a given hash.
+ *
+ * @param {object} pool - The mssql connection pool.
+ * @returns {Function} An async function that fetches a thumbnail by hash.
+ *
+ * @example
+ * const fn = getThumbByHash(pool);
+ * const thumb = await fn(42, 'abc123');
+ * // => { buffer, w, h, contentType: 'image/avif' }
+ */
 export default function getThumbByHash(pool) {
   const authorize = resolvePicAccess(pool);