feat: switch GitHub Actions to build optimized Docker image by default

- Change main build to use Dockerfile.optimized (targets ~200MB image)
- Add separate 'full' build job for development variant (2.6GB)
- Update tagging strategy: 'latest' for optimized, 'full' suffix for full variant
- Update documentation to reflect dual image strategy
- Update docker-compose.yml with variant selection comment

This provides users with two options:
- Optimized (default): Pre-built database, minimal size, for production
- Full: Complete n8n packages, dynamic scanning, for development

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

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

docker-compose.yml

@@ -3,6 +3,7 @@ version: '3.8'
 
 services:
   n8n-mcp:
+    # Use 'latest' for optimized image (~200MB) or 'full' for development (2.6GB)
     image: ghcr.io/czlonkowski/n8n-mcp:latest
     container_name: n8n-mcp
     restart: unless-stopped