fix: move demo GIF to repo root for GitHub rendering

Author: AmmarSaleh50

README.md

@@ -18,7 +18,7 @@
 ---
 
 <p align="center">
-  <img src="https://raw.githubusercontent.com/decisionnode/DecisionNode/main/website/public/demo.gif" alt="DecisionNode Demo" width="800" />
+  <img src="demo.gif" alt="DecisionNode Demo" />
 </p>
 
 Your AI keeps forgetting what you agreed on. You say "use Tailwind, no CSS modules" — next session, it writes CSS modules. DecisionNode stores these decisions as vector embeddings so the AI can search them before writing code.