feat(client): polished toolbar, live online count via SSE

- Redesign in-game client toolbar with refined glass styling and buttons
- Live online count + emulator status streamed over SSE multicast
- Who's-online tooltip throttled to reduce repeated requests
- Fix show button so it always returns the hidden toolbar
- Use theme CSS variables instead of hardcoded colors
- Add toolbar translations across all 25 locales

src/components/live-online-count.tsx

@@ -0,0 +1,33 @@
+"use client";
+
+import { useTranslations } from "next-intl";
+import { useEffect, useState } from "react";
+import { useEventSource } from "@/lib/use-event-source";
+
+/**
+ * Live online user counter. Subscribes to the SSE online-count stream so the
+ * displayed count updates in real-time (multicast) instead of only reflecting
+ * the server-rendered value at page load.
+ */
+export function LiveOnlineCount({
+	initial,
+	hotelName,
+}: {
+	initial: number;
+	hotelName: string;
+}) {
+	const t = useTranslations("header");
+	const [count, setCount] = useState(initial);
+
+	const { data: onlineStream } = useEventSource<{ count: number }>(
+		"/api/online/count/stream",
+		{ enabled: true },
+	);
+	useEffect(() => {
+		if (onlineStream && typeof onlineStream.count === "number") {
+			setCount(onlineStream.count);
+		}
+	}, [onlineStream]);
+
+	return <>{t("online", { count, hotel: hotelName })}</>;
+}