fix(customers): Add tabs to detail page and fix orders loading

Fixed 2 critical issues:

1. ✅ Orders Not Loading:
Backend (OrdersController.php):
- Added customer_id parameter support
- Lines 300-304: Filter orders by customer
- Uses WooCommerce customer_id arg

Frontend (Detail.tsx):
- Already passing customer_id correctly
- Orders will now load properly

2. ✅ Added Tabs for Better Organization:
Implemented 3-tab layout:

**Overview Tab:**
- Stats cards: Total Orders, Total Spent, Registered
- Contact information (email, phone)
- Clean, focused view

**Orders Tab:**
- Full order history (not just 10)
- Order count display
- Better empty state
- All orders clickable to detail

**Address Tab:**
- Billing address (full details)
- Shipping address (full details)
- Company names if available
- Phone in billing section
- Empty states for missing addresses

Benefits:
✅ Clean, organized, contextual data per tab
✅ No information overload
✅ Easy navigation between sections
✅ Better mobile experience
✅ Consistent with modern admin UX

Technical:
- Uses shadcn/ui Tabs component
- Responsive grid layouts
- Proper empty states
- Type-safe with TypeScript

Result: Customer detail page is now properly organized with working order history!

includes/Api/OrdersController.php

@@ -296,6 +296,12 @@ class OrdersController {
     if ( $search && preg_match( '/^#?(\\d+)$/', $search, $m ) ) {
       $args['include'] = [ absint( $m[1] ) ];
     }
+    
+    // Optional customer filter
+    $customer_id = $req->get_param( 'customer_id' );
+    if ( $customer_id ) {
+      $args['customer_id'] = absint( $customer_id );
+    }
   
     $result = wc_get_orders( $args );