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/CustomerOrderForm.tsx

@@ -23,7 +23,7 @@ import {
 } from "@/components/ui/select";
 import { Checkbox } from "@/components/ui/checkbox";
 import { insertCustomerOrderFrontendSchema, type CustomerOrderWithRelations, type Group, type Supplier } from "@shared/schema";
-import { useStore } from "@/components/Layout";
+import { useStore } from "@/contexts/StoreContext";
 
 const customerOrderFormSchema = z.object({
   orderTaker: z.string().min(1, "Qui a pris la commande est requis"),