feat: add warehouse and bin management API with mock data implementation

- Implemented warehouses API with methods for listing, creating, and managing bins.
- Added wastage API to handle stock write-offs and integrate with stock adjustments.
- Created auth token management for storing and retrieving access tokens.
- Developed error mapping for consistent user-facing error messages.
- Introduced client-side validations for GRN, master data, and procurement processes.
- Defined common types for pagination, problem details, and various master data entities.
- Established procurement and stock management types to support frontend functionality.

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

@@ -4,13 +4,18 @@ import { useEffect, useState } from "react"
 import Link from "next/link"
 import { usePathname } from "next/navigation"
 import {
+  Building2,
   ChevronRight,
+  ClipboardList,
   HelpCircle,
   LayoutGrid,
   Menu,
   Package,
+  PackageCheck,
   Settings,
   ShoppingCart,
+  Truck,
+  Warehouse,
   X,
   type LucideIcon,
 } from "lucide-react"
@@ -20,6 +25,11 @@ import { cn } from "@/lib/utils"
 const navItems: { title: string; href: string; icon: LucideIcon; chevron?: boolean }[] = [
   { title: "Dashboard", href: "/dashboard", icon: LayoutGrid },
   { title: "Products", href: "/dashboard/products", icon: Package, chevron: true },
+  { title: "Vendors", href: "/dashboard/vendors", icon: Truck, chevron: true },
+  { title: "Procurement", href: "/dashboard/procurement", icon: ClipboardList, chevron: true },
+  { title: "Receiving", href: "/dashboard/receiving/grn", icon: PackageCheck, chevron: true },
+  { title: "Stock", href: "/dashboard/stock", icon: Warehouse, chevron: true },
+  { title: "Warehouses", href: "/dashboard/warehouse", icon: Building2, chevron: true },
   { title: "Orders", href: "/dashboard/orders", icon: ShoppingCart, chevron: true },
   { title: "Settings", href: "/dashboard/settings", icon: Settings, chevron: true },
   { title: "Help", href: "/dashboard/help", icon: HelpCircle },

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

@@ -0,0 +1,84 @@
+"use client"
+
+import { Fragment } from "react"
+import Link from "next/link"
+import { usePathname } from "next/navigation"
+
+import { Breadcrumb, BreadcrumbItem, BreadcrumbList, BreadcrumbPage, BreadcrumbSeparator } from "@/components/ui/breadcrumb"
+
+// Per-segment display labels. Deliberately separate from Header.tsx's
+// titleFromPath (which resolves one *full* path to a page title) — a
+// breadcrumb needs a label per *segment*, including grouping segments that
+// have no page of their own (e.g. "receiving", "grn").
+const SEGMENT_LABELS: Record<string, string> = {
+  dashboard: "Dashboard",
+  products: "Items",
+  uoms: "UOMs",
+  categories: "Categories",
+  new: "New",
+  edit: "Edit",
+  vendors: "Vendors",
+  warehouse: "Warehouses",
+  receiving: "Receiving",
+  grn: "Goods Receipt Notes",
+  stock: "Stock",
+  enquiry: "Enquiry",
+  ledger: "Ledger",
+  valuation: "Valuation",
+  transfers: "Transfers",
+  adjustments: "Adjustments",
+  counts: "Counts",
+  "reorder-alerts": "Reorder Alerts",
+  wastage: "Wastage",
+  procurement: "Procurement",
+  requisitions: "Requisitions",
+  rfqs: "RFQs",
+  "purchase-orders": "Purchase Orders",
+  "purchase-returns": "Purchase Returns",
+}
+
+function labelFor(segment: string): string {
+  if (SEGMENT_LABELS[segment]) return SEGMENT_LABELS[segment]
+  if (/^[0-9]+$/.test(segment)) return `#${segment}`
+  return segment.charAt(0).toUpperCase() + segment.slice(1)
+}
+
+const linkClass =
+  "truncate transition-colors hover:text-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring rounded-sm"
+
+export function Breadcrumbs() {
+  const pathname = usePathname() || "/dashboard"
+  const segments = pathname.split("/").filter(Boolean)
+
+  // Nothing to show above the dashboard root itself.
+  if (segments.length <= 1) return null
+
+  const crumbs = segments.map((segment, i) => ({
+    href: "/" + segments.slice(0, i + 1).join("/"),
+    label: labelFor(segment),
+  }))
+
+  return (
+    <Breadcrumb className="mb-4">
+      <BreadcrumbList>
+        {crumbs.map((crumb, i) => {
+          const isLast = i === crumbs.length - 1
+          return (
+            <Fragment key={crumb.href}>
+              <BreadcrumbItem>
+                {isLast ? (
+                  <BreadcrumbPage>{crumb.label}</BreadcrumbPage>
+                ) : (
+                  <Link href={crumb.href} className={linkClass}>
+                    {crumb.label}
+                  </Link>
+                )}
+              </BreadcrumbItem>
+              {!isLast && <BreadcrumbSeparator />}
+            </Fragment>
+          )
+        })}
+      </BreadcrumbList>
+    </Breadcrumb>
+  )
+}

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

@@ -17,7 +17,60 @@ import {
 } from "@/components/ui/dropdown-menu"
 import { Popover, PopoverContent, PopoverTrigger } from "@/components/ui/popover"
 
+const PROCUREMENT_TITLES: Record<string, string> = {
+  "/dashboard/procurement": "Procurement",
+  "/dashboard/procurement/requisitions": "Requisitions",
+  "/dashboard/procurement/requisitions/new": "New Requisition",
+  "/dashboard/procurement/rfqs": "RFQs",
+  "/dashboard/procurement/rfqs/new": "New RFQ",
+  "/dashboard/procurement/purchase-orders": "Purchase Orders",
+  "/dashboard/procurement/purchase-orders/new": "New Purchase Order",
+  "/dashboard/procurement/purchase-returns": "Purchase Returns",
+  "/dashboard/procurement/purchase-returns/new": "New Purchase Return",
+}
+
+const STOCK_TITLES: Record<string, string> = {
+  "/dashboard/stock": "Stock Management",
+  "/dashboard/stock/enquiry": "Stock Enquiry",
+  "/dashboard/stock/ledger": "Stock Ledger",
+  "/dashboard/stock/valuation": "Valuation",
+  "/dashboard/stock/transfers": "Stock Transfers",
+  "/dashboard/stock/transfers/new": "New Transfer",
+  "/dashboard/stock/adjustments": "Stock Adjustments",
+  "/dashboard/stock/adjustments/new": "New Adjustment",
+  "/dashboard/stock/counts": "Stock Counts",
+  "/dashboard/stock/counts/new": "New Count",
+  "/dashboard/stock/reorder-alerts": "Reorder Alerts",
+  "/dashboard/stock/wastage": "Wastage",
+  "/dashboard/stock/wastage/new": "Record Wastage",
+}
+
 function titleFromPath(pathname: string) {
+  if (pathname === "/dashboard/receiving/grn") return "Goods Receipt Notes"
+  if (pathname === "/dashboard/receiving/grn/new") return "Create Goods Receipt Note"
+  if (/^\/dashboard\/receiving\/grn\/[^/]+$/.test(pathname)) return "Goods Receipt Note"
+
+  if (STOCK_TITLES[pathname]) return STOCK_TITLES[pathname]
+  if (/^\/dashboard\/stock\/transfers\/[^/]+$/.test(pathname)) return "Stock Transfer"
+  if (/^\/dashboard\/stock\/counts\/[^/]+$/.test(pathname)) return "Stock Count"
+
+  if (PROCUREMENT_TITLES[pathname]) return PROCUREMENT_TITLES[pathname]
+  if (/^\/dashboard\/procurement\/requisitions\/[^/]+$/.test(pathname)) return "Requisition"
+  if (/^\/dashboard\/procurement\/rfqs\/[^/]+$/.test(pathname)) return "RFQ"
+  if (/^\/dashboard\/procurement\/purchase-orders\/[^/]+$/.test(pathname)) return "Purchase Order"
+
+  if (pathname === "/dashboard/warehouse") return "Warehouses"
+  if (/^\/dashboard\/warehouse\/[^/]+$/.test(pathname)) return "Warehouse"
+
+  if (pathname === "/dashboard/vendors") return "Vendors"
+  if (/^\/dashboard\/vendors\/[^/]+$/.test(pathname)) return "View Vendor"
+
+  if (pathname === "/dashboard/products") return "Items"
+  if (pathname === "/dashboard/products/new") return "New Item"
+  if (pathname === "/dashboard/products/uoms") return "Units of Measure"
+  if (pathname === "/dashboard/products/categories") return "Categories"
+  if (/^\/dashboard\/products\/[^/]+$/.test(pathname)) return "Item"
+
   const segment = pathname.split("/").filter(Boolean).pop() ?? "dashboard"
   return segment.charAt(0).toUpperCase() + segment.slice(1)
 }