## ADDED Requirements

### Requirement: Per-tag SMS alert toggle
The tag edit form SHALL let the owner enable or disable SMS alerts for that tag (`sms_enabled`). The default for new and existing tags SHALL be enabled.

#### Scenario: Disable alerts
- **WHEN** the owner unchecks "Send SMS alerts when scanned" and saves
- **THEN** the tag's `sms_enabled` is false and no alerts are sent for future scans (scans are still recorded)

#### Scenario: Re-enable alerts
- **WHEN** the owner checks the option and saves
- **THEN** the tag's `sms_enabled` is true and alerts resume per the alerting rules
