fix(client): 修复入库/出库单列表供应商和仓库显示为空

fromJson 读 json['warehouse']['name'] 而非不存在的 json['warehouse_name']，
partner 同理。后端返回的是嵌套对象而非扁平字段。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/models/stock_in.dart

@@ -84,11 +84,11 @@ class StockInOrder {
         orderNo: json['order_no'] as String,
         type: json['type'] as String?,
         warehouseId: (json['warehouse_id'] as num).toInt(),
-        warehouseName: json['warehouse_name'] as String?,
+        warehouseName: (json['warehouse'] as Map<String, dynamic>?)?['name'] as String?,
         partnerId: json['partner_id'] != null
             ? (json['partner_id'] as num).toInt()
             : null,
-        partnerName: json['partner_name'] as String?,
+        partnerName: (json['partner'] as Map<String, dynamic>?)?['name'] as String?,
         operatorId: json['operator_id'] != null
             ? (json['operator_id'] as num).toInt()
             : null,

client/lib/models/stock_out.dart

@@ -72,11 +72,11 @@ class StockOutOrder {
         orderNo: json['order_no'] as String,
         type: json['type'] as String?,
         warehouseId: (json['warehouse_id'] as num).toInt(),
-        warehouseName: json['warehouse_name'] as String?,
+        warehouseName: (json['warehouse'] as Map<String, dynamic>?)?['name'] as String?,
         partnerId: json['partner_id'] != null
             ? (json['partner_id'] as num).toInt()
             : null,
-        partnerName: json['partner_name'] as String?,
+        partnerName: (json['partner'] as Map<String, dynamic>?)?['name'] as String?,
         operatorId: json['operator_id'] != null
             ? (json['operator_id'] as num).toInt()
             : null,