fix: add max-width content container for desktop layout

Content was stretching full-width on 1920px screens. Added
800px max-width centered container in AppShell, fixed nav
overflow for scrollable items.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/layout/AppShell.tsx

@@ -12,7 +12,9 @@ export function AppShell() {
       <div className="flex-1 flex flex-col min-h-dvh lg:mr-[72px]">
         <Header />
         <main className="flex-1 pb-[calc(var(--bottom-nav-height)+env(safe-area-inset-bottom))] lg:pb-0">
+          <div className="w-full max-w-[800px] mx-auto lg:px-6">
             <Outlet />
+          </div>
         </main>
         <div className="lg:hidden">
           <BottomNav />

src/components/layout/DesktopNav.tsx

@@ -15,8 +15,8 @@ const navItems = [
 
 export function DesktopNav() {
   return (
-    <nav className="hidden lg:flex fixed right-0 top-0 bottom-0 w-[72px] flex-col items-center py-6 gap-2 bg-bg-1 border-l border-white/6 z-50">
-      <span className="text-gold font-bold text-sm font-latin mb-6">E3</span>
+    <nav className="hidden lg:flex fixed right-0 top-0 bottom-0 w-[72px] flex-col items-center py-4 gap-1 bg-bg-1 border-l border-white/6 z-50 overflow-y-auto scrollbar-none">
+      <span className="text-gold font-bold text-sm font-latin mb-4">E3</span>
       {navItems.map((item) => (
         <NavLink
           key={item.to}