docs: add demo GIF to README for better conversions

- Add syncable-cli-demo.gif right after intro section
- Remove GIF from .gitignore so it's tracked
- Optimal placement: users read what it does → see demo → Quick Start

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: 2 people

.gitignore

@@ -38,5 +38,4 @@ syncable-ide-companion/*.vsix
 syncable-ide-companion/node_modules/
 syncable-ide-companion/dist/
 
-syncable-cli.tape
-syncable-cli-demo.gif
+syncable-cli.tape

README.md

@@ -53,6 +53,10 @@ You: Now add Redis caching and create a docker-compose
 Agent: I'll add Redis to your stack and create a compose file...
 ```
 
+<p align="center">
+  <img src="syncable-cli-demo.gif" alt="Syncable CLI Demo" width="800" />
+</p>
+
 ## ⚡ Quick Start
 
 ```bash