- fix(email): transactional emails are all not sent if `Use system wide (transactional) email settings` is disabled and no other email provide is setup on the Notifications page
- fix(email): no emails are sent if SMTP username and SMTP password are empty (which is the case in dev for example)
- fix(email): Wrong test email notification is used, causing the transactional email test notification to fail if no email provider is set up on the Notifications page.
- Replace `! $type` checks with `blank($type)` for consistency
- Modify email settings configuration to handle null/disabled states
- Ensure proper fallback and configuration of email providers
