feat: Add enableSubagents configuration and wire up subagent registration (#9988)

packages/cli/src/config/settingsSchema.ts

@@ -1001,6 +1001,15 @@ const SETTINGS_SCHEMA = {
           'Enable model routing to route requests to the best model based on complexity.',
         showInDialog: true,
       },
+      enableSubagents: {
+        type: 'boolean',
+        label: 'Enable Subagents',
+        category: 'Experimental',
+        requiresRestart: true,
+        default: false,
+        description: 'Enable experimental subagents.',
+        showInDialog: false,
+      },
     },
   },