pr-demo-video

Analyze a screen recording and add a demo section as a comment on the linked GitHub issue for the current PR on bbvch-ai/aihub-core. Extracts frames with ffmpeg, describes what the video shows using vision, posts the demo as an issue comment, and checks off matching test plan items on the PR. Use when user says 'add demo video to PR', 'add video to PR', 'describe the video', 'add screen recording to PR', or 'pr…