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/models/inventory.dart

@@ -79,12 +79,19 @@ class InventorySummary {
   final double inStockQty;
   final int shortageCount;
   final int warningCount;
+  // 月初快照（KPI 环比）：由 inventory_logs 反推
+  final int lastMonthSku;
+  final double lastMonthQty;
+  final double lastMonthValue;
   const InventorySummary({
     this.skuCount = 0,
     this.stockValue = 0,
     this.inStockQty = 0,
     this.shortageCount = 0,
     this.warningCount = 0,
+    this.lastMonthSku = 0,
+    this.lastMonthQty = 0,
+    this.lastMonthValue = 0,
   });
   factory InventorySummary.fromJson(Map<String, dynamic> j) => InventorySummary(
         skuCount: (j['sku_count'] as num?)?.toInt() ?? 0,
@@ -92,6 +99,9 @@ class InventorySummary {
         inStockQty: (j['in_stock_qty'] as num?)?.toDouble() ?? 0,
         shortageCount: (j['shortage_count'] as num?)?.toInt() ?? 0,
         warningCount: (j['warning_count'] as num?)?.toInt() ?? 0,
+        lastMonthSku: (j['last_month_sku'] as num?)?.toInt() ?? 0,
+        lastMonthQty: (j['last_month_qty'] as num?)?.toDouble() ?? 0,
+        lastMonthValue: (j['last_month_value'] as num?)?.toDouble() ?? 0,
       );
 }
 
@@ -138,8 +148,7 @@ class InventoryLog {
             ? (json['qty_after'] as num).toDouble()
             : null,
         refType: json['ref_type'] as String?,
-        refId:
-            json['ref_id'] != null ? (json['ref_id'] as num).toInt() : null,
+        refId: json['ref_id'] != null ? (json['ref_id'] as num).toInt() : null,
         createdAt: json['created_at'] as String?,
       );
 }