refactor: make optimized Dockerfile the default - remove full variant

- Rename Dockerfile.optimized to Dockerfile (now the default)
- Keep old Dockerfile as Dockerfile.old for reference
- Update GitHub Actions to use default Dockerfile
- Remove build-full job - only one image variant now
- Remove docker-compose.optimized.yml and other variants
- Update all documentation to reflect single image approach

The optimized 283MB image is now the only n8n-MCP Docker image.
This simplifies the user experience and provides the best solution
for all use cases.

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

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

README.md

@@ -65,9 +65,7 @@ npm run test-nodes
 
 ## Docker Quick Start 🐳
 
-The easiest way to get started is using Docker. We provide two image variants:
-- **Optimized** (`latest`): ~200MB, pre-built database, recommended for production
-- **Full** (`full`): 2.6GB, includes n8n packages, for development/dynamic scanning
+The easiest way to get started is using Docker:
 
 ### Option 1: Simple HTTP Server (Recommended)