feat(home): 所有角色主页统一嵌入产品展示页(storefront)——删除冗余产品展示菜单项

用户要求(2026-09-06)：所有人的主页都显示产品展示，简单化。
- home 标签 content 改为 urlwidget 嵌 /product_management/storefront/index.ui
  (原「产线平台」标题占位页)——未登录访客/客户/管理员统一
- 客户分支删除 product_showcase 菜单项(主页已接管，冗余)
- 其他角色菜单不动

本地验证: Jinja三角色渲染+JSON合法+home=urlwidget指向storefront+菜单无重复无残留

wwwroot/index.ui

@@ -152,12 +152,6 @@
                 "target": "app.main_content",
                 "items": [
 {% if is_customer and not is_admin %}
-                  {
-                    "name": "product_showcase",
-                    "label": "产品展示",
-                    "icon": "",
-                    "script": "this.open_tab({name:'product_showcase',label:'产品展示',url:'/product_management/storefront/index.ui',removable:true})"
-                  },
                   {
                     "name": "cust_account",
                     "label": "我的账户",
@@ -608,28 +602,10 @@
                 "label": "主页",
                 "removable": false,
                 "content": {
-                  "widgettype": "VBox",
+                  "widgettype": "urlwidget",
                   "options": {
-                    "width": "100%",
+                    "url": "{{entire_url('/product_management/storefront/index.ui')}}"
-                    "padding": "40px",
+                  }
-                    "spacing": "16px"
-                  },
-                  "subwidgets": [
-                    {
-                      "widgettype": "Title2",
-                      "options": {
-                        "text": "产线平台"
-                      }
-                    },
-                    {
-                      "widgettype": "Text",
-                      "options": {
-                        "text": "管理产线定义、运营配置、分销渠道与任务执行",
-                        "cfontsize": 1.2,
-                        "color": "#64748b"
-                      }
-                    }
-                  ]
                 }
               }
             ]