💄 Update navigation links for authenticated users

Add "Requests" and "Webhooks" links to the navigation bar for better
accessibility to user features.

💄 Add account stats card to user profile edit page

Introduce a new card displaying available credits, total requests, and member since date for enhanced user information.

💄 Update UI styles for forms and cards

Refine the appearance of forms and cards across various views to enhance
the overall user experience and maintain consistency in design.

✨ Introduce user email notifications

Add email notifications for various user actions including welcome, low credits, credits depleted, credits purchased, new login, and API key regeneration. Update email templates for better styling and user experience.