docs(qa): before/after evidence for the mobile feedback-button collision

Captured at 390x844 on /dashboard/student/courses/1001/lessons/1001 as the
seeded student. The before frame reproduces master exactly: `autoInject`
flipped back on and our own puck hidden, so only Sentry's actor is present.
Intersection math on that frame puts 72% of the "Next" button under it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FJ4dqwXuyKUPtg11ni5BSb

Author: guillermoscript