Show live online-players count on the home screen

- OnlineService.getOnlineCount(); mock random-walks a believable number,
  SignalrService reads GET /api/stats/online (server tracks hub connections)
- Home screen badge with pulsing dot, polls every 8s, localized digits

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib/online/signalr-service.ts

@@ -262,6 +262,19 @@ export class SignalrService implements OnlineService {
   markRead(id: string) { return this.mock.markRead(id); }
   onChat(cb: (id: string, m: ChatMessage[]) => void) { return this.mock.onChat(cb); }
 
+  async getOnlineCount(): Promise<number> {
+    try {
+      const res = await fetch(`${SERVER}/api/stats/online`);
+      if (res.ok) {
+        const j = (await res.json()) as { online: number };
+        return j.online ?? 0;
+      }
+    } catch {
+      /* fall through */
+    }
+    return this.mock.getOnlineCount();
+  }
+
   getLeaderboard(): Promise<LeaderboardEntry[]> { return this.mock.getLeaderboard(); }
   getShopItems(): Promise<ShopItem[]> { return this.mock.getShopItems(); }
   buyItem(id: string) { return this.mock.buyItem(id); }