feat(procurement): enhance purchase order and GRN functionalities

- Updated purchase order descriptions for clarity on draft and submission processes.
- Implemented submit and delete functionalities for draft purchase orders, allowing users to manage their orders more effectively.
- Added discount and VAT fields to GRN lines, enabling better cost tracking and reporting.
- Enhanced validation for GRN lines to ensure discount and VAT percentages are within acceptable ranges.
- Updated API to support new functionalities, including submitting and deleting purchase orders.
- Improved UI components for better user experience in managing purchase orders and GRNs.
- Documented changes in security and backend phase documentation to reflect new processes and requirements.

Frontend/erp-system/components/Layouts/AppSidebar.tsx

@@ -8,12 +8,14 @@ import {
   Building2,
   ChevronRight,
   ClipboardList,
+  FileText,
   HelpCircle,
   LayoutGrid,
   ListTree,
   Menu,
   Package,
   PackageCheck,
+  PackageX,
   Ruler,
   Settings,
   ShieldCheck,
@@ -56,7 +58,19 @@ const navItems: {
     ],
   },
   { title: "Vendors", code: "vendors", href: "/dashboard/vendors", icon: Truck, chevron: true },
-  { title: "Procurement", code: "procurement", href: "/dashboard/procurement", icon: ClipboardList, chevron: true },
+  {
+    title: "Procurement",
+    code: "procurement",
+    href: "/dashboard/procurement",
+    icon: ClipboardList,
+    chevron: true,
+    children: [
+      { title: "Requisitions", code: "procurement.requisitions", href: "/dashboard/procurement/requisitions", icon: ClipboardList },
+      { title: "RFQs", code: "procurement.rfqs", href: "/dashboard/procurement/rfqs", icon: FileText },
+      { title: "Purchase Orders", code: "procurement.purchase-orders", href: "/dashboard/procurement/purchase-orders", icon: ShoppingCart },
+      { title: "Purchase Returns", code: "procurement.purchase-returns", href: "/dashboard/procurement/purchase-returns", icon: PackageX },
+    ],
+  },
   { title: "Receiving", code: "receiving", href: "/dashboard/receiving/grn", icon: PackageCheck, chevron: true },
   { title: "Stock", code: "stock", href: "/dashboard/stock", icon: Warehouse, chevron: true },
   { title: "Warehouses", code: "warehouses", href: "/dashboard/warehouse", icon: Building2, chevron: true },