feat(dashboard): grid wallpaper on all standalone screens + fluid 4K layout (#4158)

Integrated into release/v3.8.29

src/shared/components/ErrorPageScaffold.tsx

@@ -31,7 +31,7 @@ export default function ErrorPageScaffold({
 
   return (
     <main
-      className="min-h-screen bg-bg text-text-main flex items-center justify-center px-6 py-12"
+      className="min-h-screen text-text-main flex items-center justify-center px-6 py-12"
       role="main"
       aria-labelledby="error-page-title"
     >

src/shared/components/layouts/DashboardLayout.tsx

@@ -102,7 +102,10 @@ export default function DashboardLayout({ children }) {
         />
         {!isE2EMode && <MaintenanceBanner />}
         <div className="flex-1 min-h-0 overflow-y-auto overflow-x-hidden custom-scrollbar p-4 sm:p-6 lg:p-10">
-          <div className="max-w-7xl mx-auto w-full h-full min-h-0 flex flex-col">
+          {/* Fluid up to a 4K cap (3840px): content follows the viewport on large
+              monitors and only centers (side gutters) beyond ~4K, instead of the prior
+              1280px cap that left big empty margins on wide screens. */}
+          <div className="max-w-[3840px] mx-auto w-full h-full min-h-0 flex flex-col">
             <Breadcrumbs />
             <div className="flex-1 min-h-0">
               {children}