Add Stripe Connect integration for payment processing

Updated ENVIRONMENT_VARIABLES.md to include Stripe Connect configuration details.
Modified prisma/schema.prisma to add fields for Stripe Connect account ID and tokens.
Enhanced the banking settings page to allow users to connect and disconnect their Stripe accounts.
Updated API routes to handle payment link creation using Stripe Connect.
Improved admin dashboard to display metrics related to user growth and subscription data.
Added error handling and user feedback for Stripe connection status.
Refactored components to ensure proper loading states and data handling.