style: restore blue accents for AI dialog components and standardize gold header

memento-note/app/(main)/layout.tsx

@@ -36,7 +36,7 @@ export default async function MainLayout({
           <Sidebar user={session?.user} />
         </Suspense>
 
-        <main className="memento-paper-texture flex min-h-0 flex-1 flex-col overflow-y-auto scroll-smooth">
+        <main className="flex min-h-0 flex-1 flex-col overflow-y-auto scroll-smooth bg-background">
           {children}
         </main>
 

memento-note/app/(main)/settings/data/page.tsx

@@ -127,7 +127,7 @@ export default function DataSettingsPage() {
         {/* Export card */}
         <div className="bg-card rounded-xl border border-border p-6 shadow-sm flex flex-col justify-between transition-all hover:shadow-md">
           <div className="space-y-4">
-            <div className="w-12 h-12 rounded-full bg-blue-500/10 flex items-center justify-center text-blue-600 shrink-0">
+            <div className="w-12 h-12 rounded-full bg-zinc-500/10 flex items-center justify-center text-zinc-600 shrink-0">
               <Download className="h-6 w-6" />
             </div>
             <div>