feat(client): 登录/注册页照原型重建，ds 真相源组件族统一全部屏

- 登录/注册（login.html/register.html 1:1）：两栏卡片+品牌渐变面板+主题小衣服
  pill（onSurface 变体）+记住我（记录并预填最近账号）+原型式 toast 校验；
  登录 fidelity 1.4–2.1% 三主题全绿；注册暂不入闸（少 门店编号/兑换券 字段，
  已记 CONTRACT，screens.mjs 留存根）
- ds 原子补齐：DsToast（.toast 单例）/DsCheck（.check/.agree）/DsButton lg 档/
  DsSelect 替换全部旧 DropdownButton/DsField label 在上/DsInput 后缀与密码形态
- 全屏统一：对话框按钮全 DsButton、盒式输入主题钉死（visualDensity.standard、
  h38、InputDecorationTheme 渗漏修复）、图标全 lucide、JetBrains Mono 三端同源、
  BrandMark 真相源 logo、只读模式写操作全量守卫（WriteGuard+DsToast）
- 出入库列表：版式对齐原型（卡片对齐+搜索框居中）、KPI 近30天滚动、结清后
  失效财务应收应付表；商品编辑抽屉介绍库改搜索下拉、图片双击全屏预览
- 删除旧 UI 死代码：DataTableCard/FormDialog/PageScaffold/SearchChip/
  SelectProductDialog/tabStateProvider
- golden/fidelity：stock-in/out 补注册（9%）、login 入册（8%）、goldens 全量重打；
  修复 pubspec flutter_web_plugins 非法声明（CI pub get 阻断）

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JJ1g8XV1YhhmHRzhwWEW7o

client/lib/widgets/searchable_option_field.dart

@@ -1,3 +1,4 @@
+import 'package:lucide_icons_flutter/lucide_icons.dart';
 import 'dart:async';
 
 import '../core/utils/dialog_util.dart';
@@ -5,6 +6,8 @@ import 'package:flutter/material.dart';
 import '../core/responsive/responsive.dart';
 import 'package:lpinyin/lpinyin.dart';
 import '../core/theme/context_tokens.dart';
+import 'ds/ds_atoms.dart';
+import 'ds/ds_toast.dart';
 
 class OptionItem {
   final int id;
@@ -106,10 +109,10 @@ class SearchableOptionField extends StatelessWidget {
               suffixIcon: selected
                   ? GestureDetector(
                       onTap: () => onChanged(null),
-                      child: Icon(Icons.close,
+                      child: Icon(LucideIcons.x,
                           size: 14, color: context.tokens.muted),
                     )
-                  : Icon(Icons.arrow_drop_down,
+                  : Icon(LucideIcons.chevronDown,
                       size: 16, color: context.tokens.muted),
             ),
             isEmpty: !selected,
@@ -117,7 +120,7 @@ class SearchableOptionField extends StatelessWidget {
               selected ? _displayText : hint,
               style: TextStyle(
                 fontSize: 12,
-                color: selected ? Colors.black87 : context.tokens.muted,
+                color: selected ? context.tokens.text : context.tokens.muted,
               ),
               overflow: TextOverflow.ellipsis,
             ),
@@ -190,18 +193,14 @@ class _SearchDialogState extends State<_SearchDialog> {
           child: TextField(
             controller: nameCtrl,
             autofocus: true,
-            decoration: const InputDecoration(labelText: '名称', isDense: true),
+            decoration: const InputDecoration(hintText: '名称', isDense: true),
           ),
         ),
         actions: [
-          TextButton(
-            onPressed: () => Navigator.of(context).pop(false),
-            child: const Text('取消'),
-          ),
-          TextButton(
-            onPressed: () => Navigator.of(context).pop(true),
-            child: const Text('确认新增'),
-          ),
+          DsButton('取消', onPressed: () => Navigator.of(context).pop(false)),
+          DsButton('确认新增',
+              variant: DsBtnVariant.primary,
+              onPressed: () => Navigator.of(context).pop(true)),
         ],
       ),
     );
@@ -216,16 +215,12 @@ class _SearchDialogState extends State<_SearchDialog> {
         Navigator.of(context).pop(newId); // 回填并自动选中
       } else {
         setState(() => _creating = false);
-        ScaffoldMessenger.of(context).showSnackBar(
-          const SnackBar(content: Text('新增失败，请重试')),
-        );
+        showDsToast(context, '新增失败，请重试');
       }
     } catch (e) {
       if (!mounted) return;
       setState(() => _creating = false);
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text('新增失败：$e')),
-      );
+      showDsToast(context, '新增失败：$e');
     }
   }
 
@@ -254,7 +249,7 @@ class _SearchDialogState extends State<_SearchDialog> {
               autofocus: true,
               decoration: InputDecoration(
                 hintText: '搜索...',
-                prefixIcon: const Icon(Icons.search, size: 18),
+                prefixIcon: const Icon(LucideIcons.search, size: 18),
                 suffixIcon: _searching
                     ? const Padding(
                         padding: EdgeInsets.all(10),
@@ -310,7 +305,7 @@ class _SearchDialogState extends State<_SearchDialog> {
                           height: 14,
                           child: CircularProgressIndicator(strokeWidth: 2),
                         )
-                      : const Icon(Icons.add, size: 16),
+                      : const Icon(LucideIcons.plus, size: 16),
                   label: Text('新增「$kw」到基础数据',
                       style: const TextStyle(fontSize: 12)),
                 ),
@@ -320,15 +315,8 @@ class _SearchDialogState extends State<_SearchDialog> {
       ),
       actions: [
         if (widget.selectedId != null)
-          TextButton(
-            onPressed: () => Navigator.of(context).pop(-1),
-            child: Text('清除选择',
-                style: TextStyle(color: context.tokens.muted)),
-          ),
-        TextButton(
-          onPressed: () => Navigator.of(context).pop(null),
-          child: const Text('取消'),
-        ),
+          DsButton('清除选择', onPressed: () => Navigator.of(context).pop(-1)),
+        DsButton('取消', onPressed: () => Navigator.of(context).pop(null)),
       ],
     );
   }