Implement dues reminder system with monthly payment cycle

- Add API endpoint and email templates for dues reminders
- Change due date calculation from yearly to monthly billing
- Add visual status indicators for overdue and due-soon members
- Enhance member cards with status stripes and styling

utils/dues-calculations.ts

@@ -3,7 +3,7 @@ import type { Member, DuesCalculationUtils } from '~/utils/types';
 // Constants for date calculations
 export const MILLISECONDS_PER_DAY = 1000 * 60 * 60 * 24;
 export const DAYS_IN_YEAR = 365;
-export const UPCOMING_THRESHOLD_DAYS = 30;
+export const UPCOMING_THRESHOLD_DAYS = 30; // Trigger reminders 1 month before yearly due date
 
 /**
  * Calculate days between two dates