fix: use optimized GIF for README demo instead of video tag

GitHub sanitizes <video> tags in READMEs. Replace with a 15MB
optimized GIF (640px, 8fps, 128-color palette) that renders natively.

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

Author: lucianfialho

README.md

@@ -3,9 +3,7 @@
 ISAC extracts the Brand DNA from any live website — fonts, colors, design tokens, branding, and icons — and generates a production-ready design system for your Next.js project. Powered by Claude Code.
 
 <p align="center">
-  <video src="https://github.com/guataiba/isac-cli/raw/main/assets/isac-demo.mp4" autoplay loop muted playsinline width="100%">
-    ISAC benchmark — design system extraction in ~6s, $0.00 API cost
-  </video>
+  <img src="assets/isac-demo.gif" alt="ISAC benchmark — design system extraction in ~6s, $0.00 API cost" width="100%">
 </p>
 
 ## Packages