四项全0时加权取两位舍入后的更改价格，修复 72.00495→72.01 偏差

app/Console/Commands/ComputeProductMonthlyWeightedAverage.php

@@ -281,7 +281,8 @@ class ComputeProductMonthlyWeightedAverage extends Command
         $openingAmount = $adjusted === null ? null : round($openingAmountRaw, 2);
         $denominator = $openingQuantity + $purchaseQuantity;
         if ($denominator === 0.0) {
-            $weighted = $adjusted === null ? null : round($adjusted, 4);
+            // 四项全 0：加权平均单价取"更改价格"（按两位舍入后的值）。
+            $weighted = $adjusted === null ? null : round($adjusted, 2);
         } else {
             // 先除再舍入：用未舍入的期初金额与入库金额相除，最后统一保留两位。
             $weighted = round(($openingAmountRaw + $purchaseAmountRaw) / $denominator, 4);