Pixmenia v15 audit fixes

Fixed:
1. admin/settings.php parse error caused by wrong service injection.
2. Missing includes/ai_services.php inside pixboost_app.
3. Removed unrelated transformation-service files from zip root.
4. Integrated enhancer-only services into actual upload flow.
5. Added variable credit deduction/refund based on selected service.
6. OpenAI prompt now uses selected service internal prompt.
7. Secure payment badge and premium buttons are in checkout.php and app CSS.
8. Added SQL columns for service_type and credits_used.
9. Added enhancer-only service SEO title/description templates to SQL and PHP presets.

Important deployment notes:
- Run pixboost_app/sql/database.sql on database pixmenia_sql.
- Set BASE_URL in pixboost_app/includes/config.php before live launch.
- Configure Stripe and PayPal webhook URLs and secrets in admin settings.
- Use webhook confirmation for credits; success page does not add credits.
