[Feature]: Global MCP Server Configuration

## Summary
Currently, MCP servers need to be configured individually for each agent. It would be greatly beneficial to have a global/pool-based MCP configuration system similar to the Skills pool, allowing for shared MCP server access across all agents with import capabilities.

Current Behavior
- Each agent requires individual MCP server configuration
- No way to share MCP servers across multiple agents
- Manual reconfiguration needed when adding new agents

## Proposed Solution
Implement a global MCP configuration system that:
1. **Global MCP Pool**: Define MCP servers at a global level that all agents can access
2. **Import Support**: Ability to import MCP configurations from existing setups
3. **Inheritance/Override**: Agents can inherit global MCP servers and optionally override specific settings
4. **Easy Configuration**: Single point of configuration management

## Benefits
- Reduced configuration overhead
- Consistent MCP access across all agents
- Easier maintenance and updates
- Better resource utilization