feat(#142): ouvrir la modale au clic sur les cartes du dashboard admin.

Unifie le comportement des listes Parents, AM, Enfants, Gestionnaires, Admins et À valider avec le bouton d'action au survol.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/lib/widgets/admin/common/admin_user_card.dart

@@ -13,6 +13,7 @@ class AdminUserCard extends StatefulWidget {
   final Color? titleColor;
   final Color? infoColor;
   final String? vigilanceTooltip;
+  final VoidCallback? onCardTap;
 
   const AdminUserCard({
     super.key,
@@ -26,6 +27,7 @@ class AdminUserCard extends StatefulWidget {
     this.titleColor,
     this.infoColor,
     this.vigilanceTooltip,
+    this.onCardTap,
   });
 
   @override
@@ -46,11 +48,14 @@ class _AdminUserCardState extends State<AdminUserCard> {
     return MouseRegion(
       onEnter: (_) => setState(() => _isHovered = true),
       onExit: (_) => setState(() => _isHovered = false),
+      cursor: widget.onCardTap != null
+          ? SystemMouseCursors.click
+          : MouseCursor.defer,
       child: Material(
         color: Colors.transparent,
         borderRadius: BorderRadius.circular(10),
         child: InkWell(
-          onTap: () {},
+          onTap: widget.onCardTap,
           borderRadius: BorderRadius.circular(10),
           hoverColor: const Color(0x149CC5C0),
           child: Card(