style(app): widen layout to tablet size (max-w-3xl)

src/App.tsx

@@ -39,7 +39,7 @@ function App() {
   }
 
   return (
-    <main className="mx-auto flex w-full max-w-2xl min-h-dvh flex-col pb-[calc(env(safe-area-inset-bottom)+7rem)]">
+    <main className="mx-auto flex w-full max-w-3xl min-h-dvh flex-col pb-[calc(env(safe-area-inset-bottom)+7rem)]">
       <header className="sticky top-0 z-10 border-b border-gray-200 bg-white/95 px-4 pb-3 pt-[calc(env(safe-area-inset-top)+0.75rem)] backdrop-blur">
         <div className="flex h-11 items-center gap-1">
           {creating || selectedNote ? (

src/components/ErrorPage.tsx

@@ -6,7 +6,7 @@ function ErrorPage({
   message = "Désolé, la page que vous cherchez n'existe pas.",
 }: ErrorPageProps) {
   return (
-    <main className="mx-auto flex w-full max-w-2xl min-h-dvh flex-col items-center justify-center gap-6 px-4 text-center">
+    <main className="mx-auto flex w-full max-w-3xl min-h-dvh flex-col items-center justify-center gap-6 px-4 text-center">
       <p className="text-6xl font-bold text-blue-700">{code}</p>
       <div>
         <h1 className="text-2xl font-semibold">{title}</h1>