Make user name fields optional in all interfaces

Updated user management forms to make first and last name fields optional, aligning with production server requirements and fixing inconsistencies between user creation and editing.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: a8a78c07-e900-425c-a577-5b4c5894379d
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/a8a78c07-e900-425c-a577-5b4c5894379d/vetH0Gp

client/src/pages/Users.tsx

@@ -886,23 +886,21 @@ export default function UsersPage() {
             <form onSubmit={handleSubmitEdit} className="space-y-4">
               <div className="grid grid-cols-2 gap-4">
                 <div>
-                  <Label htmlFor="edit-firstName">Prénom *</Label>
+                  <Label htmlFor="edit-firstName">Prénom</Label>
                   <Input
                     id="edit-firstName"
                     value={editForm.firstName}
                     onChange={(e) => setEditForm({...editForm, firstName: e.target.value})}
-                    placeholder="Prénom"
-                    required
+                    placeholder="Prénom (optionnel)"
                   />
                 </div>
                 <div>
-                  <Label htmlFor="edit-lastName">Nom *</Label>
+                  <Label htmlFor="edit-lastName">Nom</Label>
                   <Input
                     id="edit-lastName"
                     value={editForm.lastName}
                     onChange={(e) => setEditForm({...editForm, lastName: e.target.value})}
-                    placeholder="Nom"
-                    required
+                    placeholder="Nom (optionnel)"
                   />
                 </div>
               </div>