feat: mobile nav page + suppress desktop header on /mobile/* routes

- AppNavigation returns null on /mobile/* (no more horizontal scroll)
- Mobile header: 'Pulse' title (links home) + Menu icon (links to /mobile/nav)
- /mobile/nav: full-screen nav page with touch-friendly cards
  - Mobile Views: Dashboard, Tickets, Finance (large icon cards)
  - Full Site: Quotes, Config Items, Backup, Engagement, Ticket Digest, Admin
  - Sign out button
- Bottom tab bar unchanged (Dashboard / Tickets / Finance)

components/navigation/app-navigation.tsx

@@ -195,6 +195,9 @@ export function AppNavigation() {
   const userRole = (session?.user as any)?.role || 'user';
   const isSuperAdmin = userRole === 'super-admin';
 
+  // Mobile routes have their own nav — suppress desktop header
+  if (pathname.startsWith('/mobile')) return null;
+
   const isActive = (href?: string) => {
     if (!href) return false;
     return pathname === href || pathname.startsWith(href + '/');