Improve task visibility for director and manager roles

Update `Tasks.tsx` to enable data fetching for users with 'directeur' or 'manager' roles, provided a `selectedStoreId` is present, and for 'admin' roles without store selection restrictions.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 9fcf4b21-eb0c-4e53-a567-e2ce4a6ad869
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/9fcf4b21-eb0c-4e53-a567-e2ce4a6ad869/yiEpJFx

client/src/pages/Tasks.tsx

@@ -387,7 +387,7 @@ export default function Tasks() {
         throw error;
       }
     },
-    enabled: !!user,
+    enabled: !!user && (user.role === 'admin' || (user.role === 'directeur' || user.role === 'manager' ? !!selectedStoreId : true)),
   });
 
   // Fetch users for task assignment - seulement pour admin/manager/directeur