Retake the screenshots with the shared tool, and show the whole ACP pages (#2)

The twelve gallery screenshots came from one-off scripts. The Configuration
page was cut off at the window height and had no Recent changes feed
setting. They are now taken by phpbb-release-tools' screenshots.py, with
the two ACP pages in full, and the captions match them.

Co-authored-by: Claude Sonnet 5.5 <noreply@anthropic.com>

Author: bonelifer