fix(planner): respect first day of week setting in schedule dialog

Wait for localization config to load before rendering mat-calendar
so DateAdapter.getFirstDayOfWeek() returns the user's configured value.

Fixes #5935

src/app/features/planner/dialog-schedule-task/dialog-schedule-task.component.html

@@ -31,12 +31,14 @@
 </div>
 
 <mat-dialog-content>
-  <mat-calendar
-    (keydown)="onKeyDownOnCalendar($event)"
-    [selected]="selectedDate"
-    [minDate]="minDate"
-    (selectedChange)="dateSelected($event)"
-  ></mat-calendar>
+  @if (isConfigReady()) {
+    <mat-calendar
+      (keydown)="onKeyDownOnCalendar($event)"
+      [selected]="selectedDate"
+      [minDate]="minDate"
+      (selectedChange)="dateSelected($event)"
+    ></mat-calendar>
+  }
 
   @if (isShowEnterMsg) {
     <div

src/app/features/planner/dialog-schedule-task/dialog-schedule-task.component.ts

@@ -102,6 +102,12 @@ export class DialogScheduleTaskComponent implements AfterViewInit {
   private _globalConfigService = inject(GlobalConfigService);
   private readonly _dateAdapter = inject(DateAdapter);
 
+  // Wait for localization config to be loaded before rendering calendar
+  // This ensures DateAdapter.getFirstDayOfWeek() returns the correct value
+  readonly isConfigReady = computed(
+    () => this._globalConfigService.localization() !== undefined,
+  );
+
   T: typeof T = T;
   minDate = new Date();
   readonly calendar = viewChild.required(MatCalendar);