Refactor store context and improve responsiveness across the application

Refactored the `useStore` hook to be imported from a dedicated `StoreContext` to improve code organization and maintainability. Also, enhanced responsive design for better usability on various screen sizes, including tablet-specific adjustments for the sidebar and header.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 95e8aab4-f39f-4b48-aa57-a759ec15ba3d
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/95e8aab4-f39f-4b48-aa57-a759ec15ba3d/A90CXrX

client/src/components/tasks/NewTaskForm.tsx

@@ -3,7 +3,7 @@ import { useForm } from "react-hook-form";
 import { zodResolver } from "@hookform/resolvers/zod";
 import { useMutation, useQueryClient, useQuery } from "@tanstack/react-query";
 import { useAuthUnified } from "@/hooks/useAuthUnified";
-import { useStore } from "@/components/Layout";
+import { useStore } from "@/contexts/StoreContext";
 import { useToast } from "@/hooks/use-toast";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";