fix: Implement product lookup in RecordLoss method to accurately reduce inventory on loss

src/CMSMicroservice.WebApi/Services/InventoryService.cs

@@ -222,10 +222,35 @@ public class InventoryService : InventoryContract.InventoryContractBase
         throw new RpcException(new Status(StatusCode.Unimplemented, "ProcessReturn requires product lookup - not yet implemented"));
     }
 
-    public override Task<Empty> RecordLoss(RecordLossRequest request, ServerCallContext context)
+    public override async Task<Empty> RecordLoss(RecordLossRequest request, ServerCallContext context)
     {
-        // TODO: Implement with product lookup
-        throw new RpcException(new Status(StatusCode.Unimplemented, "RecordLoss requires product lookup - not yet implemented"));
+        // Lookup InventoryItem by ProductId + ProductType
+        var inventoryItem = await _mediator.Send(
+            new GetInventoryByProductQuery
+            {
+                ProductId = request.ProductId,
+                ProductType = (Domain.Enums.ProductType)request.ProductType
+            },
+            context.CancellationToken);
+
+        if (inventoryItem == null)
+        {
+            throw new RpcException(new Status(StatusCode.NotFound, 
+                $"Inventory item not found for ProductId={request.ProductId}, ProductType={request.ProductType}"));
+        }
+
+        // Execute ReduceInventoryCommand to record the loss
+        await _mediator.Send(
+            new ReduceInventoryCommand
+            {
+                Id = inventoryItem.Id,
+                Quantity = request.Quantity,
+                FromReserved = false,
+                ReferenceNumber = request.ReferenceNumber ?? $"LOSS-{DateTime.UtcNow:yyyyMMddHHmmss}"
+            },
+            context.CancellationToken);
+
+        return new Empty();
     }
 
     // ========== Bulk Operations ==========