feat(frontend): 对齐万华门户风格并更新全量截图文档

- 新增门户导航子页面（交易信息、政策法规、操作指南、常见问题、采购平台）并统一门户壳层样式
- 按万华站点风格重构首页与登录页（导航、轮播、公告、登录区）
- 优化小滨助手：首页/登录页接入、可拖拽吸边、圆形图标、圆形外框与切换动画优化
- 重新生成全量页面截图并更新《滨化智慧招标平台-前端界面截图汇总.docx》

Co-authored-by: Cursor <cursoragent@cursor.com>

front-end/package-lock.json

@@ -67,6 +67,7 @@
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         "@vitejs/plugin-react": "4.7.0",
+        "playwright": "^1.61.1",
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         "vite": "6.3.5"
       },
@@ -4766,6 +4767,53 @@
         "url": "https://github.com/sponsors/jonschlinkert"
       }
     },
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+      "license": "Apache-2.0",
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+      "dev": true,
+      "hasInstallScript": true,
+      "license": "MIT",
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     "node_modules/postcss": {
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