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

Backend/ERPCore/Controllers/ItemsController.cs

@@ -30,6 +30,19 @@ public sealed class ItemsController : ApiControllerBase
         CancellationToken ct)
         => Ok(await _items.ListAsync(query, status, categoryId, subCategoryId, brandId, trackingMode, ct));
 
+    /// <summary>Items list enriched with stock value, low-stock, last-purchase and
+    /// trailing-30-day sales aggregates, for the Items overview table.</summary>
+    [HttpGet("overview")]
+    [ProducesResponseType(typeof(PagedResponse<ItemOverviewDto>), StatusCodes.Status200OK)]
+    public async Task<ActionResult<PagedResponse<ItemOverviewDto>>> Overview(
+        [FromQuery] PageQuery query,
+        [FromQuery] EntityStatus? status,
+        [FromQuery] int? categoryId,
+        [FromQuery] int? subCategoryId,
+        [FromQuery] int? brandId,
+        CancellationToken ct)
+        => Ok(await _items.GetOverviewAsync(query, status, categoryId, subCategoryId, brandId, ct));
+
     /// <summary>Barcode/RFID lookup — matches an item's barcode/SKU, or a batch/serial
     /// barcode/no (optionally scoped to <paramref name="itemId"/> first).</summary>
     [HttpGet("scan")]