feat: add three new Portainer MCP servers

- Add portainer-environments server for environment/endpoint management
- Add portainer-docker server for Docker and Swarm container operations
- Add merged portainer server combining core + teams functionality
- Fix JSON schema issues and API compatibility
- Add comprehensive documentation for each server
- Add .gitignore and .env.example for security

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

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

.env.example

@@ -9,7 +9,7 @@
 #   - https://portainer.example.com
 #   - https://portainer.company.com:9443
 #   - http://localhost:9000
-PORTAINER_URL=https://portainer.example.com
+PORTAINER_URL=https://your-portainer-instance.com
 
 # Portainer API key for authentication (required)
 # Generate this from Portainer UI: User settings > API tokens
@@ -40,3 +40,6 @@ LOG_FORMAT=json
 # Development settings
 DEBUG=false
 
+# MCP mode - disables stdout logging
+MCP_MODE=true
+