Ballbox final rebrand package

Integrated into confirmed machine paths:
- F1-pay-banner -> ImagePay/46d3a954-ec76-4f45-8696-e153b4ef48be.png
- G1-side-poster -> ImageRight/a2f1d5b7-2291-4fa5-8fa3-1385218008a4.png
- D1-how-to-buy -> ImageScreen/流程图.jpg
- E1-brand-placeholder -> pollFile/Screeempty.png
- H1-ad-slot-default -> pollFile/adEmpty.png

Mapped into vendor media directories to complete the planned rebrand pass:
- A2-home-secondary -> ImageBackground/ballbox-home-secondary.png
- A2-home-secondary -> ImageScreen/ballbox-home-secondary.png
- B1-selection-screen -> ImageHelp/ballbox-help-selection.png
- C1-payment-qr -> ImageHelp/ballbox-help-payment-qr.png

Why this mapping:
- Vendor quick guide explicitly names ImageBackground, ImageHelp, ImageScreen, and VideoAndImageAd as media folders.
- This dump already had the exact 5 confirmed live assets above.
- The remaining 3 assets are now placed into the matching vendor media buckets instead of staying only as loose extras.