feat: add daily cron scheduler for price checks

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/scheduler.js

@@ -0,0 +1,10 @@
+const cronDefault = require('node-cron');
+
+const SCHEDULE = '0 8 * * *';
+const TIMEZONE = 'Europe/Amsterdam';
+
+function start(runCheck, { cron = cronDefault } = {}) {
+  return cron.schedule(SCHEDULE, runCheck, { timezone: TIMEZONE });
+}
+
+module.exports = { start, SCHEDULE, TIMEZONE };