feat(client): 出入库列表按原型重建（KPI/详情抽屉/详细搜索/工具栏/选中复制/窗口尺寸）

- 列表重建：KPI 卡、状态+时间列、操作改眼睛开右侧详情抽屉、重置右置
- 详情抽屉(order_detail_drawer) 100% 还原原型 + SelectionArea 可选中复制
- 详细搜索弹窗：ComboSearchField/滚轮日期、字段重构、白底盒子按钮
- 工具栏：搜索框×清除+占位精简、供应商/客户下拉取全部、状态菜单收窄
- 加载不白屏(半透明遮罩)、输入框与下拉等高、windows/macOS 默认窗口尺寸调大

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/lib/models/stock_summary.dart

@@ -0,0 +1,33 @@
+/// 出/入库 KPI 汇总（本月 + 上月同期供环比 + 待审核）。
+/// 对应后端 `GET /stock-in/summary`、`/stock-out/summary`。
+class StockSummary {
+  final int monthCount;
+  final double monthAmount;
+  final int pendingCount;
+  final int lastMonthCount;
+  final double lastMonthAmount;
+
+  const StockSummary({
+    this.monthCount = 0,
+    this.monthAmount = 0,
+    this.pendingCount = 0,
+    this.lastMonthCount = 0,
+    this.lastMonthAmount = 0,
+  });
+
+  factory StockSummary.fromJson(Map<String, dynamic> j) => StockSummary(
+        monthCount: (j['month_count'] as num?)?.toInt() ?? 0,
+        monthAmount: (j['month_amount'] as num?)?.toDouble() ?? 0,
+        pendingCount: (j['pending_count'] as num?)?.toInt() ?? 0,
+        lastMonthCount: (j['last_month_count'] as num?)?.toInt() ?? 0,
+        lastMonthAmount: (j['last_month_amount'] as num?)?.toDouble() ?? 0,
+      );
+
+  /// 笔数环比（%）；上月为 0 时返回 null（无从比较）。
+  double? get countDeltaPct =>
+      lastMonthCount == 0 ? null : (monthCount - lastMonthCount) / lastMonthCount * 100;
+
+  /// 金额环比（%）；上月为 0 时返回 null。
+  double? get amountDeltaPct =>
+      lastMonthAmount == 0 ? null : (monthAmount - lastMonthAmount) / lastMonthAmount * 100;
+}