Add GRN batch and serial tracking

Distribution/Models/GoodsReceipt.cs

@@ -4,9 +4,15 @@ namespace Distribution.Models
 {
     public class GoodsReceipt : Template
     {
-        public Guid FK_PurchaseOrderId { get; set; }
+        /// <summary>Null for a direct receipt (goods received without a purchase order).</summary>
+        public Guid? FK_PurchaseOrderId { get; set; }
         [ForeignKey("FK_PurchaseOrderId")]
-        public PurchaseOrder PurchaseOrder { get; set; }
+        public PurchaseOrder? PurchaseOrder { get; set; }
+
+        /// <summary>Optional supplier for a direct receipt; for PO receipts the supplier comes from the PO.</summary>
+        public Guid? FK_SupplierId { get; set; }
+        [ForeignKey("FK_SupplierId")]
+        public Supplier? Supplier { get; set; }
 
         public Guid FK_ReceivedByUserId { get; set; }
 

Distribution/Models/GoodsReceiptItem.cs

@@ -8,14 +8,26 @@ namespace Distribution.Models
         [ForeignKey("FK_GoodsReceiptId")]
         public GoodsReceipt GoodsReceipt { get; set; }
 
-        public Guid FK_PurchaseOrderItemId { get; set; }
+        /// <summary>Null for a direct receipt line (no purchase order); FK_ItemId is set instead.</summary>
+        public Guid? FK_PurchaseOrderItemId { get; set; }
         [ForeignKey("FK_PurchaseOrderItemId")]
-        public PurchaseOrderItem PurchaseOrderItem { get; set; }
+        public PurchaseOrderItem? PurchaseOrderItem { get; set; }
+
+        /// <summary>Set for direct receipt lines. PO-based lines resolve the item through PurchaseOrderItem.</summary>
+        public Guid? FK_ItemId { get; set; }
+        [ForeignKey("FK_ItemId")]
+        public Item? Item { get; set; }
 
         /// <summary>Added to warehouse stock.</summary>
         public int AcceptedQuantity { get; set; }
 
         /// <summary>Damaged/short at receipt, not added to stock.</summary>
         public int RejectedQuantity { get; set; } = 0;
+
+        /// <summary>Populated when the received item tracks batches and/or expiry dates.</summary>
+        public ICollection<GoodsReceiptItemBatch> Batches { get; set; } = [];
+
+        /// <summary>Populated when the received item tracks serial numbers.</summary>
+        public ICollection<GoodsReceiptItemSerial> Serials { get; set; } = [];
     }
 }

Distribution/Models/GoodsReceiptItemBatch.cs

@@ -0,0 +1,18 @@
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Distribution.Models
+{
+    /// <summary>One row per batch/expiry-lot split within a single GRN line.</summary>
+    public class GoodsReceiptItemBatch : Template
+    {
+        public Guid FK_GoodsReceiptItemId { get; set; }
+        [ForeignKey("FK_GoodsReceiptItemId")]
+        public GoodsReceiptItem GoodsReceiptItem { get; set; }
+
+        public Guid FK_ItemBatchId { get; set; }
+        [ForeignKey("FK_ItemBatchId")]
+        public ItemBatch ItemBatch { get; set; }
+
+        public int Quantity { get; set; }
+    }
+}

Distribution/Models/GoodsReceiptItemSerial.cs

@@ -0,0 +1,16 @@
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace Distribution.Models
+{
+    /// <summary>One row per serial number received within a single GRN line.</summary>
+    public class GoodsReceiptItemSerial : Template
+    {
+        public Guid FK_GoodsReceiptItemId { get; set; }
+        [ForeignKey("FK_GoodsReceiptItemId")]
+        public GoodsReceiptItem GoodsReceiptItem { get; set; }
+
+        public Guid FK_ItemSerialNumberId { get; set; }
+        [ForeignKey("FK_ItemSerialNumberId")]
+        public ItemSerialNumber ItemSerialNumber { get; set; }
+    }
+}