feat: add Telegram notification provider support

- Updated API to support Telegram as a notification provider type.
- Enhanced tests to cover Telegram provider creation, updates, and token handling.
- Modified frontend forms to include Telegram-specific fields and validation.
- Added localization strings for Telegram provider.
- Implemented security measures to ensure bot tokens are not exposed in API responses.

frontend/src/components/__tests__/SecurityNotificationSettingsModal.test.tsx

@@ -85,7 +85,7 @@ describe('Security Notification Settings on Notifications page', () => {
     await user.click(await screen.findByTestId('add-provider-btn'));
 
     const typeSelect = screen.getByTestId('provider-type') as HTMLSelectElement;
-    expect(Array.from(typeSelect.options).map((option) => option.value)).toEqual(['discord', 'gotify', 'webhook', 'email']);
+    expect(Array.from(typeSelect.options).map((option) => option.value)).toEqual(['discord', 'gotify', 'webhook', 'email', 'telegram']);
     expect(typeSelect.value).toBe('discord');
 
     const webhookInput = screen.getByTestId('provider-url') as HTMLInputElement;