Build an Admin Dashboard with User Management

Create an admin dashboard at /admin that is gated behind an is_admin: true flag on the users table — redirect any non-admin to /dashboard with a 403 message. The main view should be a paginated table of all users with these columns: email, full name, signup date, subscription tier (shown as a colored badge), and last active date. Add a search bar above the table that filters rows in real time by email or name. Each table row should have a "View profile" link that opens a side panel or page showing the user's full details, activity history, and subscription info. At the top of the admin page, show a stats bar with three numbers: total registered users, number of active paid subscriptions, and estimated monthly recurring revenue calculated from subscription tiers.