refactor(client): 日期选择统一为扁平组件——输入框+滚轮同宽居中入面板，桌面/移动全覆盖

- wheel_date_picker.dart 重构为统一组件：单日期 showDsDateDropdown（面板=
  可输入框+三列滚轮+今天/确定）、范围 showDateRangeDropdown（起始|结束双窗格
  并排+共用底栏）；桌面锚定下拉（透明遮罩不冻结窗口）、窄屏底部 sheet 同内容
  （范围纵排）——同一套窗格两端复用
- 扁平化：输入框与滚轮同宽 248、文字水平垂直居中(mono)、去掉全部阴影/立体
  效果（滚轮外框仅 1px 边框，中心高亮带去描边）
- DsDateCell（录单日期格）与 DatePickerField（登记收支）改为触发器：点选/
  回车打开统一面板，键入在面板内完成；出库工具栏时间 chip 补切到新组件
- 旧 showWheelDatePicker/showWheelDateRange 两步弹窗删除；组件测试改写为
  新契约（触发器+面板键入+词法归一），表单 golden 随形态更新

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

client/test/date_picker_field_test.dart

@@ -33,19 +33,7 @@ void main() {
   });
 
   group('DatePickerField', () {
-    testWidgets('渲染可键入框 + 日历图标', (tester) async {
-      await tester.pumpWidget(MaterialApp(
-        theme: buildTheme('a'),
-        home: Scaffold(
-          body: DatePickerField(value: '2026-06-19', onChanged: (_) {}),
-        ),
-      ));
-      await tester.pumpAndSettle();
-      expect(find.byType(TextField), findsOneWidget);
-      expect(find.byIcon(LucideIcons.calendar), findsOneWidget);
-    });
-
-    testWidgets('初始值回显到输入框', (tester) async {
+    testWidgets('渲染触发字段：值回显 + 日历图标', (tester) async {
       await tester.pumpWidget(MaterialApp(
         theme: buildTheme('a'),
         home: Scaffold(
@@ -54,30 +42,56 @@ void main() {
       ));
       await tester.pumpAndSettle();
       expect(find.text('2026-06-19'), findsOneWidget);
+      expect(find.byIcon(LucideIcons.calendar), findsOneWidget);
+      // 字段本体不再内嵌输入框（输入框在下拉面板里）
+      expect(find.byType(TextField), findsNothing);
     });
 
-    testWidgets('只输年份归一为 yyyy-01-01', (tester) async {
+    testWidgets('点选打开统一下拉：面板含输入框 + 滚轮，确定回传', (tester) async {
       String? out;
       await tester.pumpWidget(MaterialApp(
         theme: buildTheme('a'),
         home: Scaffold(
-          body: DatePickerField(onChanged: (v) => out = v),
+          body: DatePickerField(value: '2026-06-19', onChanged: (v) => out = v),
         ),
       ));
-      await tester.enterText(find.byType(TextField), '2024');
-      expect(out, '2024-01-01');
+      await tester.pumpAndSettle();
+      await tester.tap(find.byIcon(LucideIcons.calendar));
+      await tester.pumpAndSettle();
+      // 面板：可输入框 + 三列滚轮 + 今天/确定
+      expect(find.byType(TextField), findsOneWidget);
+      expect(find.byType(ListWheelScrollView), findsNWidgets(3));
+      expect(find.text('今天'), findsOneWidget);
+      await tester.tap(find.text('确定'));
+      await tester.pumpAndSettle();
+      expect(out, '2026-06-19');
     });
 
-    testWidgets('年月归一为 yyyy-MM-01', (tester) async {
+    testWidgets('面板内键入日期：归一并经确定回传', (tester) async {
       String? out;
       await tester.pumpWidget(MaterialApp(
         theme: buildTheme('a'),
         home: Scaffold(
-          body: DatePickerField(onChanged: (v) => out = v),
+          body: DatePickerField(value: '2026-06-19', onChanged: (v) => out = v),
         ),
       ));
-      await tester.enterText(find.byType(TextField), '2024-5');
-      expect(out, '2024-05-01');
+      await tester.pumpAndSettle();
+      await tester.tap(find.byIcon(LucideIcons.calendar));
+      await tester.pumpAndSettle();
+      await tester.enterText(find.byType(TextField), '20240512');
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('确定'));
+      await tester.pumpAndSettle();
+      expect(out, '2024-05-12');
+    });
+
+    testWidgets('normalizeYmd 词法：年/年月补 01', (tester) async {
+      expect(normalizeYmd('2024'), '2024-01-01');
+      expect(normalizeYmd('2024-5'), '2024-05-01');
+      expect(normalizeYmd('2024/05/12'), '2024-05-12');
+      expect(normalizeYmd('20240229'), '2024-02-29'); // 闰年
+      expect(normalizeYmd('20260231'), '2026-02-28'); // 超界 clamp
+      expect(normalizeYmd('abc'), isNull);
     });
   });
 }