Add inactivity timeout and polling control to seat overlay

Introduces user inactivity tracking and timeout for seat polling in TheaterOverlayComponent. Polling is paused after 2 minutes of inactivity or when the user advances past step 1, with a snackbar notification and resume option. Refactors polling logic, adds step change event to OrderComponent, and updates custom theme for snackbar styling.

src/app/order/order.component.ts

@@ -1,7 +1,7 @@
 import { SelectedSeatsService } from './../selected-seats.service';
 import { LoadingService } from './../loading.service';
 import { Bestellung, Eintrittskarte, Sitzkategorie, Sitzplatz, Vorstellung } from '@infinimotion/model-frontend';
-import { Component, computed, DestroyRef, inject, input, signal } from '@angular/core';
+import { Component, computed, DestroyRef, EventEmitter, inject, input, output, Output, signal, ViewChild } from '@angular/core';
 import { FormBuilder, FormGroup, Validators } from '@angular/forms';
 import { StepperSelectionEvent } from '@angular/cdk/stepper';
 import { HttpService } from '../http.service';
@@ -29,12 +29,15 @@ export class OrderComponent {
   private fb = inject(FormBuilder);
   private httpService = inject(HttpService);
   private destroyRef = inject(DestroyRef);
+
   readonly loadingService = inject(LoadingService);
   readonly selectedSeatsService = inject(SelectedSeatsService);
 
   performance = input<Vorstellung>();
   seatCategories = input.required<Sitzkategorie[]>();
 
+  stepChanged = output<number>();
+
   paymentForm!: FormGroup;
   dataForm!: FormGroup;
 
@@ -107,6 +110,8 @@ export class OrderComponent {
   onStepChange(event: StepperSelectionEvent) {
     this.submitted.set(false);
     this.selectedSeatsService.setSeatSelectable(event.selectedIndex === 0);
+
+    this.stepChanged.emit(event.selectedIndex);
   }
 
   reservationClicked() {