Simplify demo notice

frontend/src/App.tsx

@@ -1136,13 +1136,7 @@ export default function App() {
     <div className={`app-shell ${isWorkshopMode && activeModule === "atelier" ? "app-shell--workshop" : ""}`}>
       <main className="workspace">
         <aside className="demo-notice" role="note">
-          <strong>{t("Simulation and demonstration only", "Simulation et demonstration uniquement")}</strong>
-          <span>
-            {t(
-              "This web application is for simulation and demonstration. It must not be used as a validated production MES or safety system.",
-              "Cette application web est destinee a la simulation et a la demonstration. Elle ne doit pas etre utilisee comme MES de production valide ni comme systeme de securite.",
-            )}
-          </span>
+          <strong>Simulation et demonstration uniquement</strong>
         </aside>
 
         <header className="hero">