Add a short launch GIF from the live PR story

[AzurLiu]

Goal: add a compact GIF or screenshot sequence that shows the live PR story moving from claim_check_blocked to claim_check_ready.

Why: the current proof links are credible, but a short visual is easier to share in launch posts and issue comments.

Suggested scope:

• Reuse the existing live PR proof links and docs/assets/falsiflow_live_pr_story_reel.svg.
• Keep it under 10 seconds or use a 3-frame screenshot sequence.
• Do not add new product claims; keep the evidence-package readiness boundary visible.

Verification:

python3 scripts/falsiflow.py launch-kit --out-dir /tmp/falsiflow_launch_gif_check --force --json
python3 scripts/falsiflow.py release-check --out-dir /tmp/falsiflow_launch_gif_release_check --force --skip-dist --json