refactor(store): split gatewayStore into specialized domain stores

Major restructuring:
- Split monolithic gatewayStore into 5 focused stores:
  - connectionStore: WebSocket connection and gateway lifecycle
  - configStore: quickConfig, workspaceInfo, MCP services
  - agentStore: clones, usage stats, agent management
  - handStore: hands, approvals, triggers, hand runs
  - workflowStore: workflows, workflow runs, execution

- Update all components to use new stores with selector pattern
- Remove

desktop/src/components/Settings/MCPServices.tsx

@@ -1,9 +1,10 @@
 import { FileText, Globe } from 'lucide-react';
-import { useGatewayStore } from '../../store/gatewayStore';
+import { useConfigStore } from '../../store/configStore';
 import { silentErrorHandler } from '../../lib/error-utils';
 
 export function MCPServices() {
-  const { quickConfig, saveQuickConfig } = useGatewayStore();
+  const quickConfig = useConfigStore((s) => s.quickConfig);
+  const saveQuickConfig = useConfigStore((s) => s.saveQuickConfig);
 
   const services = quickConfig.mcpServices || [];