Every pointerup unconditionally fires finish-panning and finish-zooming,
which call finalize-view-interaction!. This triggered internal-render
(and reset_canvas) on plain clicks — causing a visible white flash on
large viewports or weak GPUs.
Add a guard so finalize-view-interaction! only runs when a view
interaction (pan/zoom) is actually active.
Fixes#10915
Co-authored-by: Cursor <cursoragent@cursor.com>