The MQTT broker URL in credential emails was using the internal Docker
address (mqtt://mosquitto:1883) which is not accessible from external
OwnTracks apps. Added MQTT_PUBLIC_BROKER_URL environment variable to
configure the publicly accessible broker address for client apps.
Changes:
- Add MQTT_PUBLIC_BROKER_URL to .env.example with documentation
- Update send-credentials route to use public URL with fallback
- Maintain backward compatibility with existing MQTT_BROKER_URL
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
