Fix member management issues and add refined view

- Sort dues management cards alphabetically by last name
- Change 'Invalid Date' display to 'N/A' in formatDate functions
- Add new refined member management view with modern UI design
  - Glassmorphism effects and gradient accents
  - Enhanced stat cards with progress indicators
  - Improved search and filter interface
  - Better card and table layouts
  - Smooth animations and transitions

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

pages/admin/members/index.vue

@@ -607,7 +607,10 @@ const getDuesColor = (status: string) => {
 };
 
 const formatDate = (date: string) => {
-  return new Date(date).toLocaleDateString('en-US', {
+  if (!date) return 'N/A';
+  const parsedDate = new Date(date);
+  if (isNaN(parsedDate.getTime())) return 'N/A';
+  return parsedDate.toLocaleDateString('en-US', {
     month: 'short',
     day: 'numeric',
     year: 'numeric'