feat(issue-222): wire angular host/player i18n to backend shell locale

frontend/angular/src/app/features/host/host-shell.component.ts

@@ -55,7 +55,7 @@ type LeaderboardResponse = FinishGameResponse;
       <pre *ngIf="scoreboardPayload">{{ scoreboardPayload }}</pre>
       <div *ngIf="finalLeaderboard.length">
         <h3>{{ copy('host.final_leaderboard') }}</h3>
-        <p *ngIf="finalWinner"><strong>{{ copy('host.winner') }}:</strong> {{ finalWinner.nickname }} ({{ finalWinner.score }} pts)</p>
+        <p *ngIf="finalWinner"><strong>{{ copy('host.winner') }}:</strong> {{ finalWinner.nickname }} ({{ finalWinner.score }} {{ copy('common.points_short') }})</p>
         <ol>
           <li *ngFor="let entry of finalLeaderboard">{{ entry.nickname }}: {{ entry.score }}</li>
         </ol>

frontend/angular/src/app/features/player/player-shell.component.ts

@@ -255,7 +255,7 @@ export class PlayerShellComponent implements OnInit, OnDestroy {
     if (error instanceof Error && error.message) {
       return error.message;
     }
-    return 'Unknown error';
+    return this.copy('common.unknown_error');
   }
 
   private markOnline(): void {

frontend/angular/src/app/lobby-i18n.spec.ts

@@ -45,6 +45,22 @@ describe('lobby i18n locale propagation', () => {
     expect(updates).toEqual(['en', 'da']);
   });
 
+  it('prefers backend-provided shell locale over browser defaults', async () => {
+    vi.stubGlobal('window', {
+      location: { search: '' },
+      localStorage: storageMock(),
+    });
+    vi.stubGlobal('document', {
+      body: { dataset: { wppLocale: 'da' } },
+      querySelector: vi.fn(() => null),
+    });
+    vi.stubGlobal('navigator', { language: 'en-US' });
+
+    const i18n = await import('./lobby-i18n');
+
+    expect(i18n.resolvePreferredLocale()).toBe('da');
+  });
+
   it('falls back to default en translation when da key is intentionally missing', async () => {
     vi.stubGlobal('window', {
       location: { search: '' },

frontend/angular/src/app/lobby-i18n.ts

@@ -32,11 +32,14 @@ export function resolvePreferredLocale(): SupportedLocale {
     return activeLocale;
   }
 
+  const rootLocale =
+    typeof document !== 'undefined' ? document.querySelector<HTMLElement>('app-root')?.dataset?.['wppLocale'] : null;
+  const shellLocale = typeof document !== 'undefined' ? document.body?.dataset?.['wppLocale'] : null;
   const queryLocale = new URLSearchParams(window.location?.search ?? '').get('lang');
   const storedLocale = window.localStorage?.getItem?.('wpp.locale');
   const browserLocale = typeof navigator !== 'undefined' ? navigator.language : '';
 
-  activeLocale = normalizeLocale(queryLocale || storedLocale || browserLocale || DEFAULT_LOCALE);
+  activeLocale = normalizeLocale(rootLocale || shellLocale || queryLocale || storedLocale || browserLocale || DEFAULT_LOCALE);
   return activeLocale;
 }