SmartLabel Pro Online License Backend

1. Upload this smartlabel_backend folder to your PHP hosting.
2. Create MySQL database and import schema.sql.
3. Edit config.php with DB username/password and APP_SECRET.
4. In Windows app online_config.json, set:
   api_base_url = https://yourdomain.com/smartlabel_backend/api
   app_secret = same APP_SECRET from config.php
5. Admin login:
   URL: https://yourdomain.com/smartlabel_backend/admin/login.php
   User: admin
   Pass: admin123
   Change password after setup.

Main flow:
- Customer registers from app.
- Backend creates customer + PC device + 15-day trial.
- Admin approves/renews for 365 days.
- App caches license locally for offline usage.
- App queues print usage locally and syncs slowly when internet is available.
- Admin customer page shows consumed labels, supplied labels and balance by label size.
