fix: move AdminScopeToggle from NavDrawer to main header bar

Places the scope toggle next to the UserMenu avatar in the top-right
header area so it's always visible without opening the nav drawer.

frontend/src/components/NavDrawer.js

@@ -1,7 +1,6 @@
 import React from 'react';
 import { X, Home, BarChart2, BookOpen, Download, ShieldCheck, Settings, Ticket } from 'lucide-react';
 import { useAuth } from '../contexts/AuthContext';
-import AdminScopeToggle from './AdminScopeToggle';
 
 const NAV_ITEMS = [
   { id: 'home',           label: 'Home',           icon: Home,        color: '#0EA5E9', description: 'Main dashboard'            },
@@ -64,12 +63,6 @@ export default function NavDrawer({ isOpen, onClose, currentPage, onNavigate })
 
         {/* Nav items */}
         <nav style={{ display: 'flex', flexDirection: 'column', gap: '0.375rem' }}>
-
-          {/* Admin scope toggle — between header and nav items */}
-          <div style={{ marginBottom: '0.5rem' }}>
-            <AdminScopeToggle />
-          </div>
-
           {NAV_ITEMS.map(({ id, label, icon: Icon, color, description }) => {
             const active = currentPage === id;
             return (