docs(q8b): replace board and interface images

[tzz-radxa]

Summary

• Replace the Dragon Q8B appearance and numbered interface images with the updated product artwork.
• Reuse the existing shared asset paths for the Chinese and English product and hardware pages.

Why

The current interface illustration does not show the 50-pin B2B connector on the rear of the board. The new illustration adds label 13 and renumbers the following labels through 23.

Verification

• Visually inspected both converted WebP files; the interface image includes labels 1-23.
• Ran pre-commit run --files on both assets and the paired content files.
• Local PR guard: one static scope, two files, no reasons.