feat: MFA frontend with auth page restyling, challenge screen, and setup wizard

- Restyle organizer auth pages: Dutch text, remove placeholder social login
- Restyle portal auth pages to Vuexy v1 centered card pattern with decorative shapes
- MFA challenge card component with VOtpInput, method tabs, backup code input,
  trusted device checkbox, and session countdown timer
- Login pages handle mfa_required response with device fingerprint header
- Security settings page with TOTP setup (QR code), email setup, disable MFA,
  backup codes regeneration, and trusted devices management
- Portal profile page includes MFA security section
- Admin user detail page shows MFA status with reset button
- MFA enforcement route guard redirects to security settings when required
- Device fingerprint utility for trusted device identification
- MFA types, composables with TanStack Query for both apps

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/app/src/layouts/components/UserProfile.vue

@@ -87,6 +87,17 @@ function handleLogout() {
           <VListItemTitle>Accountinstellingen</VListItemTitle>
         </VListItem>
 
+        <VListItem :to="{ name: 'account-settings-security' }">
+          <template #prepend>
+            <VIcon
+              class="me-2"
+              icon="tabler-shield-lock"
+              size="22"
+            />
+          </template>
+          <VListItemTitle>Beveiliging</VListItemTitle>
+        </VListItem>
+
         <VListItem
           :disabled="isLoggingOut"
           @click="handleLogout"