fix: allow 6-field cron expressions with seconds

The cron editor rejected sub-minute expressions like `*/30 * * * * *`
because validation required exactly 5 fields. Now accepts both 5-field
(standard) and 6-field (with seconds) cron expressions.

Also fixes schedule type auto-detection to correctly fall back to
'custom' for 6-field expressions instead of misinterpreting field
positions.

Fixes #819

src/routes/api/auto-update/[containerName]/+server.ts

@@ -66,7 +66,7 @@ export const POST: RequestHandler = async ({ params, url, request, cookies }) =>
 		let scheduleType: 'daily' | 'weekly' | 'custom' = 'custom';
 		if (cronExpression) {
 			const parts = cronExpression.split(' ');
-			if (parts.length >= 5) {
+			if (parts.length === 5) {
 				const [, , day, month, dow] = parts;
 				if (dow !== '*' && day === '*' && month === '*') {
 					scheduleType = 'weekly';