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/messages/nl.json

@@ -3265,5 +3265,18 @@
 				}
 			}
 		}
+	},
+	"toolbar": {
+		"home": "Home",
+		"reload": "Vernieuwen",
+		"fullscreen": "Volledig scherm",
+		"logout": "Uitloggen",
+		"onlineUsers": "Gebruikers online",
+		"emulatorOnline": "Emulator online",
+		"emulatorOffline": "Emulator offline",
+		"dragToMove": "Sleep om te verplaatsen",
+		"hide": "Werkbalk verbergen",
+		"fullscreenExit": "Volledig scherm afsluiten",
+		"show": "Werkbalk tonen"
 	}
 }