docs: extend README demo with AI mode (flag browser + NL2SH + compare)

Re-records the home-screen demo at the readable 92x30 geometry and appends
the AI feature: English->bash one-liner generation and side-by-side model
A/B, so the README clip now showcases the full feature set in one take.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -11,9 +11,10 @@ descriptions, and jump back to the command list instantly.
 Video (MP4): [`demo/super-man-demo.mp4`](demo/super-man-demo.mp4) ·
 asciinema cast: [`demo/super-man-demo.cast`](demo/super-man-demo.cast)
 
-The clip shows opening an entry (`grep`), browsing its flags, then pressing
-**Esc** to return straight to the home screen — no intermediary step — and
-repeating with `tar`.
+The clip fuzzy-filters to `chmod`, opens its flag browser to scroll the
+options with live man-page descriptions, then **Esc** back to the home
+screen — and finishes with AI mode: turning plain English into a bash
+one-liner and A/B-ing two local models side by side.
 
 ### Themes