feat(client): 录单表单优化 + 可搜索下拉支持新建 + 日期选择器组件

新增 DatePickerField 日期选择器与 date_util；可搜索下拉 SearchableOptionField
支持内联新建选项；入库/出库录单表单、商品页、财务页、app_shell 导航相应调整。

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

client/lib/core/router/app_router.dart

@@ -20,8 +20,7 @@ import '../../screens/about/about_screen.dart';
 import '../../screens/devices/device_management_screen.dart';
 import '../auth/auth_state.dart';
 
-Page<void> _noTransition(Widget child) =>
-    NoTransitionPage<void>(child: child);
+Page<void> _noTransition(Widget child) => NoTransitionPage<void>(child: child);
 
 /// ChangeNotifier that bridges Riverpod auth state → GoRouter refreshListenable.
 class _RouterNotifier extends ChangeNotifier {
@@ -94,74 +93,106 @@ final appRouterProvider = Provider<GoRouter>((ref) {
         path: '/login',
         builder: (context, state) => const LoginScreen(),
       ),
-      ShellRoute(
-        builder: (context, state, child) => AppShell(child: child),
-        routes: [
-          GoRoute(
-              path: '/stock-in',
-              pageBuilder: (_, __) => _noTransition(const StockInListScreen())),
-          GoRoute(
-              path: '/stock-in/new',
-              pageBuilder: (_, __) => _noTransition(const StockInFormScreen())),
-          GoRoute(
-              path: '/stock-in/edit/:id',
-              pageBuilder: (_, state) => _noTransition(
-                  StockInFormScreen(
-                      editOrderId: int.parse(state.pathParameters['id']!)))),
-          GoRoute(
-              path: '/stock-out',
-              pageBuilder: (_, __) => _noTransition(const StockOutListScreen())),
-          GoRoute(
-              path: '/stock-out/new',
-              pageBuilder: (_, __) => _noTransition(const StockOutFormScreen())),
-          GoRoute(
-              path: '/stock-out/edit/:id',
-              pageBuilder: (_, state) => _noTransition(
-                  StockOutFormScreen(
-                      editOrderId: int.parse(state.pathParameters['id']!)))),
-          GoRoute(
-              path: '/inventory',
-              pageBuilder: (_, __) =>
-                  _noTransition(const InventoryListScreen())),
-          GoRoute(
-              path: '/inventory/check',
-              pageBuilder: (_, __) =>
-                  _noTransition(const InventoryCheckScreen())),
-          GoRoute(
-              path: '/partners',
-              pageBuilder: (_, __) => _noTransition(const PartnersScreen())),
-          GoRoute(
-              path: '/finance',
-              pageBuilder: (_, __) => _noTransition(const FinanceScreen())),
-          GoRoute(
-              path: '/products',
-              pageBuilder: (_, __) => _noTransition(const ProductsScreen())),
-          GoRoute(
-              path: '/products/:id',
-              pageBuilder: (_, state) => _noTransition(ProductDetailScreen(
-                  productId: int.parse(state.pathParameters['id']!)))),
-          GoRoute(
-              path: '/settings',
-              pageBuilder: (_, state) {
-                const tabIndex = {
-                  'shop': 0,
-                  'users': 1,
-                  'number': 2,
-                  'system': 3,
-                  'license': 4,
-                  'import': 5,
-                };
-                final tab =
-                    tabIndex[state.uri.queryParameters['tab']] ?? 0;
-                return _noTransition(SettingsScreen(initialTab: tab));
-              }),
-          GoRoute(
-              path: '/devices',
-              pageBuilder: (_, __) =>
-                  _noTransition(const DeviceManagementScreen())),
-          GoRoute(
-              path: '/about',
-              pageBuilder: (_, __) => _noTransition(const AboutScreen())),
+      // 各栏目拆为独立分支：StatefulShellRoute.indexedStack 让每个分支的 Navigator
+      // 及其页面 State 常驻，跨栏目切换不再销毁上一页（半填表单/内部 tab/滚动位置保活）。
+      // 分支顺序必须与 AppShell._navItems 一致（navigationShell.currentIndex 据此高亮）。
+      StatefulShellRoute.indexedStack(
+        builder: (context, state, navigationShell) =>
+            AppShell(navigationShell: navigationShell),
+        branches: [
+          // 0 入库管理
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/stock-in',
+                pageBuilder: (_, __) =>
+                    _noTransition(const StockInListScreen())),
+            GoRoute(
+                path: '/stock-in/new',
+                pageBuilder: (_, __) =>
+                    _noTransition(const StockInFormScreen())),
+            GoRoute(
+                path: '/stock-in/edit/:id',
+                pageBuilder: (_, state) => _noTransition(StockInFormScreen(
+                    editOrderId: int.parse(state.pathParameters['id']!)))),
+          ]),
+          // 1 出库管理
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/stock-out',
+                pageBuilder: (_, __) =>
+                    _noTransition(const StockOutListScreen())),
+            GoRoute(
+                path: '/stock-out/new',
+                pageBuilder: (_, __) =>
+                    _noTransition(const StockOutFormScreen())),
+            GoRoute(
+                path: '/stock-out/edit/:id',
+                pageBuilder: (_, state) => _noTransition(StockOutFormScreen(
+                    editOrderId: int.parse(state.pathParameters['id']!)))),
+          ]),
+          // 2 库存管理
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/inventory',
+                pageBuilder: (_, __) =>
+                    _noTransition(const InventoryListScreen())),
+            GoRoute(
+                path: '/inventory/check',
+                pageBuilder: (_, __) =>
+                    _noTransition(const InventoryCheckScreen())),
+          ]),
+          // 3 财务管理
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/finance',
+                pageBuilder: (_, __) => _noTransition(const FinanceScreen())),
+          ]),
+          // 4 往来单位
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/partners',
+                pageBuilder: (_, __) => _noTransition(const PartnersScreen())),
+          ]),
+          // 5 基础数据
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/products',
+                pageBuilder: (_, __) => _noTransition(const ProductsScreen())),
+            GoRoute(
+                path: '/products/:id',
+                pageBuilder: (_, state) => _noTransition(ProductDetailScreen(
+                    productId: int.parse(state.pathParameters['id']!)))),
+          ]),
+          // 6 设备管理
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/devices',
+                pageBuilder: (_, __) =>
+                    _noTransition(const DeviceManagementScreen())),
+          ]),
+          // 7 系统设置
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/settings',
+                pageBuilder: (_, state) {
+                  const tabIndex = {
+                    'shop': 0,
+                    'users': 1,
+                    'number': 2,
+                    'system': 3,
+                    'license': 4,
+                    'import': 5,
+                  };
+                  final tab = tabIndex[state.uri.queryParameters['tab']] ?? 0;
+                  return _noTransition(SettingsScreen(initialTab: tab));
+                }),
+          ]),
+          // 8 关于我们
+          StatefulShellBranch(routes: [
+            GoRoute(
+                path: '/about',
+                pageBuilder: (_, __) => _noTransition(const AboutScreen())),
+          ]),
         ],
       ),
     ],