feat(trash): 商品删除→垃圾桶(软删可恢复)+ 左侧垃圾桶入口

后端(无需迁移,复用 Product.status active/archived):
- destroy 改软删(status→archived);正常列表/详情只看 active
- 新增 /products/trash(列已删)、/products/{id}/restore(恢复)、/{id}/purge(彻底删)
- tests.py:软删/列表隐藏/回收站/恢复/彻底删/拒绝彻底删 active —— 5 测试全过

前端:
- api:productsTrash / restoreProduct / purgeProduct
- 左侧导航加「垃圾桶」(新增 trash 图标);route-config 接 /trash 路由
- 新页 routes/trash.tsx + trash-page.css(仅 token):已删商品列表 + 恢复 + 彻底删(二次确认)
- 删除确认文案「不可撤销」→「移至垃圾桶可恢复」;toast「商品已删除」→「已移至垃圾桶」

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

core/frontend/src/components/app-shell.tsx

@@ -195,6 +195,7 @@ const NAV: NavDef[] = [
   { id: "library", page: "library", label: "资产库", icon: "library" },
   { id: "team", page: "team", label: "团队", icon: "users" },
   { id: "account", page: "account", label: "消费", icon: "creditCard" },
+  { id: "trash", page: "trash", label: "垃圾桶", icon: "trash" },
   { id: "settings", page: "settings", label: "设置", icon: "settings" }
 ];