Optimisations and updated readme

src/data/playlists.js

@@ -1,5 +1,5 @@
 async function fetchPlaylistById(pool, id) {
-  const [rows] = await pool.query('SELECT * FROM playlists WHERE id = ?', [id]);
+  const [rows] = await pool.query('SELECT id, name, fade_between_slides, created_at, modified_at, created_by, modified_by FROM playlists WHERE id = ?', [id]);
   return rows[0] || null;
 }