- Add comprehensive billing page with current subscription display and transaction history
- Integrate Polar.sh customer portal for subscription management
- Fix Polar API endpoint from /customer-portal to /customer-sessions
- Use Polar's direct customer_portal_url response for seamless redirect
- Add responsive button layout with cursor-pointer styling
- Implement human-readable timestamps using diffForHumans()
- Add subscription sync functionality with 30-minute recheck window
- Include subscription cancellation with modal confirmation
- Support activation key provider with pending activation display
- Add proper error handling and user feedback messages
