fix: include priority field in ticket list API response

Priority was missing from the tickets list endpoint,
so colors weren't showing in the ticket table.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api.php

@@ -1604,6 +1604,7 @@ switch ($action) {
                     'customer_id' => $t['customer_id'] ?? '',
                     'customer_name' => $t['customer_name'] ?? '',
                     'tags' => $t['tags'] ?? [],
+                    'priority' => $t['priority'] ?? 'normaali',
                     'auto_close_at' => $t['auto_close_at'] ?? '',
                     'mailbox_id' => $t['mailbox_id'] ?? '',
                     'mailbox_name' => $mailboxNames[$t['mailbox_id'] ?? ''] ?? '',