feat: add ItemOverviewDto for enriched item data in items list

feat: implement CustomerDetailPage for detailed customer view and editing

feat: create CustomersPage for listing and managing customers with filters

feat: add ColumnsMenu component for customizable table columns visibility

feat: implement CSV export functionality for data download

feat: add customer code generation logic for unique customer identifiers

Frontend/erp-system/lib/api/customers.ts

@@ -1,15 +1,35 @@
-import { apiRequest, buildQuery } from "@/lib/api-client"
-import { PagedResponse } from "@/types/common"
-import { Customer } from "@/types/customers"
+// One typed client method per customer endpoint. ETag/If-Match on update, PATCH status
+// for deactivate (masters are deactivated, not hard-deleted, FR-MD-08).
+import { apiRequest, apiRequestWithETag, buildQuery } from "@/lib/api-client"
+import { ApiResult, EntityStatus, PagedResponse } from "@/types/common"
+import { CreateCustomerRequest, Customer, CustomerType, UpdateCustomerRequest } from "@/types/customers"
 
 export interface ListCustomersParams {
   page?: number
   pageSize?: number
   q?: string
+  status?: EntityStatus
+  customerType?: CustomerType
 }
 
 export const customersApi = {
   list(params: ListCustomersParams = {}): Promise<PagedResponse<Customer>> {
     return apiRequest<PagedResponse<Customer>>(`/customers${buildQuery(params)}`)
   },
+
+  get(customerId: number): Promise<ApiResult<Customer>> {
+    return apiRequestWithETag<Customer>(`/customers/${customerId}`)
+  },
+
+  create(request: CreateCustomerRequest): Promise<ApiResult<Customer>> {
+    return apiRequestWithETag<Customer>("/customers", { method: "POST", body: request })
+  },
+
+  update(customerId: number, request: UpdateCustomerRequest, ifMatch: string): Promise<ApiResult<Customer>> {
+    return apiRequestWithETag<Customer>(`/customers/${customerId}`, { method: "PUT", body: request, ifMatch })
+  },
+
+  updateStatus(customerId: number, status: EntityStatus): Promise<void> {
+    return apiRequest<void>(`/customers/${customerId}/status`, { method: "PATCH", body: { status } })
+  },
 }

Frontend/erp-system/lib/api/items.ts

@@ -6,6 +6,7 @@ import {
   CreateItemRequest,
   Item,
   ItemListItem,
+  ItemOverview,
   ItemReorderSetting,
   ItemScanResult,
   TrackingMode,
@@ -25,11 +26,27 @@ export interface ListItemsParams {
   sort?: string
 }
 
+export interface ListItemOverviewParams {
+  page?: number
+  pageSize?: number
+  q?: string
+  status?: EntityStatus
+  categoryId?: number
+  subCategoryId?: number
+  brandId?: number
+}
+
 export const itemsApi = {
   list(params: ListItemsParams = {}): Promise<PagedResponse<ItemListItem>> {
     return apiRequest<PagedResponse<ItemListItem>>(`/items${buildQuery(params)}`)
   },
 
+  /** Items list enriched with stock value, low-stock, last-purchase and 30-day sales
+   * aggregates — backs the Items overview table, not the lightweight document pickers. */
+  overview(params: ListItemOverviewParams = {}): Promise<PagedResponse<ItemOverview>> {
+    return apiRequest<PagedResponse<ItemOverview>>(`/items/overview${buildQuery(params)}`)
+  },
+
   get(itemId: number): Promise<ApiResult<Item>> {
     return apiRequestWithETag<Item>(`/items/${itemId}`)
   },