docs(prompt): add guide videos to all six prompt guides

[abhijaisrivastava15]

What

All six Prompt guide pages now open with a video of the real product doing the thing the page describes.

Page	Video	Length
Create a prompt	create-a-prompt.mp4	43s
Run a prompt	run-a-prompt.mp4	14s
Commit & compare versions	commit-and-compare-versions.mp4	27s
Evaluate prompt outputs	evaluate-prompt-outputs.mp4	50s
Organize prompts in folders	organize-prompts-in-folders.mp4	25s
Track prompt performance	track-prompt-performance.mp4	27s

How they were shot

• 2800x1626, native retina. Captured at 2x pixel density and never downscaled.
• No browser chrome. The tab bar and URL bar are cropped off to the pixel, so every frame is platform only.
• Real product, real data, on app.futureagi.com. Nothing is a mockup or a slideshow.
• A cursor visibly travels to each control, hovers, and clicks. Every click is a real trusted event, so hover menus open and ripples fire.
• Each one is time compressed so it reads in well under a minute.

Placement

Each video sits right after the page intro, using the same <video autoPlay muted loop playsInline> block already used by the Knowledge Base and Protect guides, with a one line italic caption under it.

Size

14.0 MB across six files. Everything is +faststart, so playback starts before the file finishes downloading.

Closes TH-7526.