chore(deps): update Angular core/cli/animations/common/compiler/forms/platform-browser/router/service-worker 21.1.5 -> 22.0.8

Ran via ng update @angular/core@22 @angular/cli@22 (schematics applied
automatically). TypeScript bumped 5.9.3 -> 6.0.3 as a required peer.

Migrations applied:
- provideHttpClient() calls gained withXhr() where HttpXhrBackend is used
  (app.config.ts)
- optional-chaining expressions wrapped in $safeNavigationMigration()
  (language-selector.component.html)
- nullishCoalescingNotNullable/optionalChainNotNullable extended
  diagnostics disabled in tsconfig.app.json/tsconfig.spec.json (matches
  the new stricter default the migration works around)

Next: ng update @angular/cdk@22, then verify tsc/build/tests.

src/app/components/language-selector/language-selector.component.html

@@ -1,7 +1,7 @@
 <div class="language-selector" role="listbox">
   <button class="language-button" (click)="toggleDropdown()" (keydown)="onKeyDown($event)" aria-haspopup="listbox" [attr.aria-expanded]="dropdownOpen">
-    <img [src]="languageService.getCurrentLanguage()?.flagSvg" 
-         [alt]="languageService.getCurrentLanguage()?.name" 
+    <img [src]="$safeNavigationMigration(languageService.getCurrentLanguage()?.flagSvg)" 
+         [alt]="$safeNavigationMigration(languageService.getCurrentLanguage()?.name)" 
          class="language-flag">
     <span class="language-code">{{ languageService.getCurrentLanguage()?.code?.toUpperCase() }}</span>
     <app-icon name="chevronDown" [size]="14" [class.rotated]="dropdownOpen" class="dropdown-arrow" />