Add storyboard contact sheet flow and runtime prereq surfacing

[justinTM]

Summary

• Add optional storyboard generation to proofshot stop and a standalone proofshot storyboard command.
• Keep the generated proof compact in PR comments: one overview image and at most two key screenshots.
• Surface runtime prerequisites in proofshot install so agent-browser and ffmpeg show up in the repo’s install flow.

Validation

• npm test
• npm run build
• git diff --check

Proof

• Ran the sample-app fixture through proofshot start -> proofshot exec -> proofshot stop --storyboard.
• Verified the recorded session, storyboard output, and trimmed PR comment flow on commit 30a8351.

[justinTM]

ProofShot Verification

Verify all 3 pages load: home, dashboard, settings

✅ No errors detected

What this shows

• A short video of the full run
• One overview image when available
• At most two screenshots that show the key state change

Recording

Session recording

Overview

Key screenshots

Before: dashboard

After: settings

---

_{Branch: justintm/storyboard-contact-sheet · Commit: 30a8351 · 1 session(s)
Generated by ProofShot}