docs(evidence): add before/after comparison stills for #562

PNGs are gitignored repo-wide (temporary screenshots), so the paired
before/after stills ship as GIFs alongside the flow recording.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KZVsJNvmfUsbT4WY83ePKE

Author: guillermoscript