feat(mcp): add Model Context Protocol integration

Add  MCP integration including:
- New MCP settings tab with server configuration
- Tool invocation UI components
- API endpoints for MCP management
- Integration with chat system for tool execution
- Example configurations

app/components/@settings/core/ControlPanel.tsx

@@ -33,7 +33,7 @@ interface ControlPanelProps {
 }
 
 // Beta status for experimental features
-const BETA_TABS = new Set<TabType>(['service-status', 'local-providers']);
+const BETA_TABS = new Set<TabType>(['service-status', 'local-providers', 'mcp']);
 
 const BetaLabel = () => (
   <div className="absolute top-2 right-2 px-1.5 py-0.5 rounded-full bg-purple-500/10 dark:bg-purple-500/20">