Fix issue where multiple page reloads are needed to see selected store's tasks

Update React Query cache invalidation to include `/api/tasks` and ensure automatic cache invalidation when the selected store changes.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: e437ffed-c31b-44eb-9fd5-b6f9faa8e7ce
Replit-Commit-Checkpoint-Type: full_checkpoint

client/src/pages/Tasks.tsx

@@ -266,7 +266,7 @@ export default function Tasks() {
     }
   };
 
-  const getDueDateStatus = (dueDate: string | null, status: string) => {
+  const getDueDateStatus = (dueDate: Date | string | null, status: string) => {
     if (!dueDate || status === 'completed') return null;
     
     const due = new Date(dueDate);