fix: resolve DataTables and Chart.js errors from restored original

- Removed invalid chart.min.css link (Chart.js 4.x has no separate CSS)
- Fixed DataTables initialization:
  - leadsTable: 7 columns, sort by date (column 3), no pagination
  - fullLeadsTable: 10 columns, sort by date (column 6), with pagination
- Tables initialized separately to avoid column index mismatch
- Fixed Uncaught TypeError: aDataSort undefined

public/admin.html

@@ -14,7 +14,6 @@
     <!-- Google Fonts -->
     <link href="https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap" rel="stylesheet">
     <!-- Chart.js -->
-    <link href="https://cdn.jsdelivr.net/npm/chart.js@4.4.1/dist/chart.min.css" rel="stylesheet">
     <!-- DataTables -->
     <link href="https://cdn.jsdelivr.net/npm/datatables.net-bs5@1.13.8/css/dataTables.bootstrap5.min.css" rel="stylesheet">
     <!-- Lightpick -->
@@ -2830,15 +2829,35 @@ Ver todos
             }
         });
 
-        // Initialize DataTables
-        $('#leadsTable, #fullLeadsTable').DataTable({
-            language: {
-                url: 'https://cdn.datatables.net/plug-ins/1.13.8/i18n/es-ES.json'
-            },
-            pageLength: 10,
-            ordering: true,
-            order: [[6, 'desc']]
-        });
+        // Initialize DataTables separately for each table
+        // leadsTable: 7 columns (Cliente, Email, Teléfono, Fecha, Estado, Acciones + hidden)
+        // fullLeadsTable: 10 columns (checkbox, Cliente, Contacto, Propiedad, Presupuesto, Fuente, Fecha, Estado, Acciones)
+        
+        if ($('#leadsTable').length) {
+            $('#leadsTable').DataTable({
+                language: {
+                    url: 'https://cdn.datatables.net/plug-ins/1.13.8/i18n/es-ES.json'
+                },
+                pageLength: 5,
+                ordering: true,
+                order: [[3, 'desc']],
+                searching: false,
+                lengthChange: false,
+                info: false,
+                paging: false
+            });
+        }
+        
+        if ($('#fullLeadsTable').length) {
+            $('#fullLeadsTable').DataTable({
+                language: {
+                    url: 'https://cdn.datatables.net/plug-ins/1.13.8/i18n/es-ES.json'
+                },
+                pageLength: 10,
+                ordering: true,
+                order: [[6, 'desc']]
+            });
+        }
 
         // ============ CHARTS ============
         const chartColors = {