The replay canvas panned without limit, so a drag could push the map and
its dot grid off screen into empty space. The camera now holds the world
box over the part of the canvas the roster leaves clear, as the editor's
canvas does, and the follow camera goes through the same clamp, so a
player at the map edge stays in view, as centred as the edge allows.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>