docs(evidence): before/after screenshots and flow GIF for #562

Visual proof for the free-offering fix: the products list before (the
published free offering is absent) and after, the public one-click free
enrollment, and a recording of the whole admin→student flow.

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

Author: guillermoscript