feat: polish toolbar, live online count via SSE + emulator 3-state

- Add emulator status 3-state (unknown/green/red) with tooltip
- Extract shared primary button style/constants for DRY toolbar code
- Add emulatorUnknown translations to all 25 locales
- Bump Next.js to 16.3.4
- Fix RCON delivery timeout caching (15s TTL / shared across clients)
- Who's-online tooltip throttled to max 1 request per 30s

src/messages/pt.json

@@ -3275,6 +3275,7 @@
 		"dragToMove": "Arraste para mover",
 		"hide": "Ocultar barra",
 		"fullscreenExit": "Sair da tela cheia",
-		"show": "Mostrar barra"
+		"show": "Mostrar barra",
+		"emulatorUnknown": "Estado do emulador desconhecido"
 	}
 }