fix(unit-3): Add settings/profile routes, move profile to UserMenu

- Add /settings (Owner only) and /profile routes under authenticatedRoute
  so sidebar stays visible and layout is preserved
- Create SettingsPage and ProfilePage placeholder components (coming soon)
- Remove Profile nav item from Sidebar — profile now accessible via UserMenu
- Add Profile link to UserMenu dropdown above logout
- Update Sidebar tests to reflect profile-free nav

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/components/layout/Sidebar.tsx

@@ -1,6 +1,6 @@
 import { Link } from '@tanstack/react-router';
 import { useTranslation } from 'react-i18next';
-import { LayoutDashboard, Users, FileText, Settings, User, X } from 'lucide-react';
+import { LayoutDashboard, Users, FileText, Settings, X } from 'lucide-react';
 import type { LucideIcon } from 'lucide-react';
 import { cn } from '@/lib/utils';
 import { useAuth } from '@/contexts/auth-context';
@@ -23,7 +23,6 @@ const NAV_ITEMS: NavItem[] = [
     { to: '/users', labelKey: 'nav.users', icon: Users, testId: 'nav-users', roles: ['Owner', 'Administrator'] },
     { to: '/settings', labelKey: 'nav.settings', icon: Settings, testId: 'nav-settings', roles: ['Owner'] },
     { to: '/cms', labelKey: 'nav.cms', icon: FileText, testId: 'nav-cms', roles: ['Owner'] },
-    { to: '/profile', labelKey: 'nav.profile', icon: User, testId: 'nav-profile' },
 ];
 
 interface SidebarProps {