fix(examples): drop the dead interrupt existence guard in the demo shell

LangGraphAgent.interrupt is now a required member, so `agent.interrupt &&`
is always true and the packaged-consumer build rejects it with TS2774.
The call itself still returns AgentInterrupt | undefined, so the remaining
`agent.interrupt()` test is the real condition.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: blove

examples/chat/angular/src/app/shell/demo-shell.component.html

@@ -135,7 +135,7 @@
       <app-itinerary-panel class="demo-shell__itinerary-overlay" />
       <div class="demo-shell__main">
         <router-outlet />
-        @if (agent.interrupt && agent.interrupt()) {
+        @if (agent.interrupt()) {
           <div class="demo-shell__interrupt-panel" role="region" aria-label="Approval required">
             <chat-interrupt-panel [agent]="agent" (action)="onInterruptAction($event)" />
           </div>
@@ -148,7 +148,7 @@
       [attr.data-sidenav-mode]="sidenavMode() !== 'drawer' ? sidenavMode() : null"
     >
       <router-outlet />
-      @if (agent.interrupt && agent.interrupt()) {
+      @if (agent.interrupt()) {
         <div class="demo-shell__interrupt-panel" role="region" aria-label="Approval required">
           <chat-interrupt-panel [agent]="agent" (action)="onInterruptAction($event)" />
         </div>