feat(core): agnostic background task UI with CompletionBehavior (#22740)

Co-authored-by: mkorwel <matt.korwel@gmail.com>

packages/core/src/tools/shell.ts

@@ -357,6 +357,8 @@ export class ShellToolInvocation extends BaseToolInvocation<
               this.context.config.sanitizationConfig,
             sandboxManager: this.context.config.sandboxManager,
             additionalPermissions: this.params[PARAM_ADDITIONAL_PERMISSIONS],
+            backgroundCompletionBehavior:
+              this.context.config.getShellBackgroundCompletionBehavior(),
           },
         );