feat(client): KPI 图标改用 lucide（与原型同源图形库）

原型图标源自 lucide-static（icons.js）。引入 lucide_icons_flutter 包，
库存屏 KPI 图标改 LucideIcons.box/database/box/triangleAlert，与原型一模一样
（不再用 Material 凑近似）。golden_harness 加载 Lucide package 字体（family 带
packages/ 前缀），golden 正确渲染。flutter test 242 通过。

后续：侧栏/顶栏/状态栏图标也逐步换 lucide（对照 shell.js）。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TSKEiHsvauyxYUW2itzUXX

client/lib/screens/inventory/inventory_list_screen.dart

@@ -15,6 +15,7 @@ import '../../widgets/write_guard.dart';
 import '../../providers/inventory_provider.dart';
 import '../../widgets/data_table_card.dart';
 import '../../widgets/kpi_card.dart' show StatusPill; // 旧 tab/移动卡片用，待统一 DsBadge
+import 'package:lucide_icons_flutter/lucide_icons.dart';
 import '../../widgets/ds/ds_atoms.dart';
 import '../../widgets/ds/ds_kpi.dart';
 import '../../widgets/ds/ds_table.dart';
@@ -646,7 +647,7 @@ class _InventoryListScreenState extends ConsumerState<InventoryListScreen> {
                   title: 'SKU 总数',
                   value: NumberFormat.decimalPattern()
                       .format(summary?.skuCount ?? result.total),
-                  icon: Icons.inventory_2,
+                  icon: LucideIcons.box,
                   tone: DsKpiTone.info,
                   delta: '点击清筛选',
                   onTap: () {
@@ -666,7 +667,7 @@ class _InventoryListScreenState extends ConsumerState<InventoryListScreen> {
                 DsKpi(
                   title: '库存货值',
                   value: summary != null ? yuanWan(summary.stockValue) : '—',
-                  icon: Icons.savings_outlined,
+                  icon: LucideIcons.database,
                   tone: DsKpiTone.ok,
                   delta: '按进价',
                 ),
@@ -674,14 +675,14 @@ class _InventoryListScreenState extends ConsumerState<InventoryListScreen> {
                   title: '在库数量',
                   value: NumberFormat.decimalPattern()
                       .format((summary?.inStockQty ?? 0).round()),
-                  icon: Icons.warehouse_outlined,
+                  icon: LucideIcons.box,
                   tone: DsKpiTone.blue,
                   delta: '件',
                 ),
                 DsKpi(
                   title: '缺货预警',
                   value: '${summary?.shortageCount ?? 0}',
-                  icon: Icons.error_outline,
+                  icon: LucideIcons.triangleAlert,
                   tone: DsKpiTone.alert,
                   delta: (summary?.warningCount ?? 0) > 0
                       ? '需补货 ${summary!.warningCount} 项'