Enhance VpnConfigDto to include ClientEmail and update related components

- Added ClientEmail property to VpnConfigDto for better client identification.
- Updated ConfigCard to display the ClientEmail in the UI for improved user information.
- Modified API schema and types to accommodate the new ClientEmail field.
- Enhanced localization for displaying the ClientEmail in both Russian and English.

frontend/src/shared/lib/i18n.ts

@@ -87,6 +87,7 @@ const resources = {
         copyLink: 'Скопировать ссылку',
         loadingLink: 'Загрузка ссылки…',
         subscriptionLink: 'Ссылка-подписка (для клиента):',
+        panelEmail: 'Email в панели: {{email}}',
         aggregatedSubscription: 'Общая подписка',
         aggregatedSubscriptionHint: 'Одна ссылка/QR со всеми активными конфигами — удобно добавить один раз в клиент.',
         status: {
@@ -379,6 +380,7 @@ const resources = {
         copyLink: 'Copy link',
         loadingLink: 'Loading link…',
         subscriptionLink: 'Subscription link (for the client app):',
+        panelEmail: 'Panel email: {{email}}',
         aggregatedSubscription: 'Aggregated subscription',
         aggregatedSubscriptionHint: 'One link/QR with all active configs — add it once to your client.',
         status: {