feat: 公开统计功能增强 - 独立设置栏目和双Y轴折线图

- 将公开统计设置从品牌设置移至独立栏目
- 用三合一双Y轴折线图替代条形图（Chart.js + vue-chartjs）
- 左Y轴显示Tokens，右Y轴显示活跃数量
- 添加暂无数据状态的友好提示
- 修复Y轴可能显示负数的问题（设置min:0）

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

web/admin-spa/package-lock.json

@@ -15,6 +15,7 @@
         "element-plus": "^2.4.4",
         "pinia": "^2.1.7",
         "vue": "^3.3.4",
+        "vue-chartjs": "^5.3.3",
         "vue-router": "^4.2.5",
         "xlsx": "^0.18.5",
         "xlsx-js-style": "^1.2.0"
@@ -5131,6 +5132,16 @@
         }
       }
     },
+    "node_modules/vue-chartjs": {
+      "version": "5.3.3",
+      "resolved": "https://registry.npmjs.org/vue-chartjs/-/vue-chartjs-5.3.3.tgz",
+      "integrity": "sha512-jqxtL8KZ6YJ5NTv6XzrzLS7osyegOi28UGNZW0h9OkDL7Sh1396ht4Dorh04aKrl2LiSalQ84WtqiG0RIJb0tA==",
+      "license": "MIT",
+      "peerDependencies": {
+        "chart.js": "^4.1.1",
+        "vue": "^3.0.0-0 || ^2.7.0"
+      }
+    },
     "node_modules/vue-demi": {
       "version": "0.14.10",
       "resolved": "https://registry.npmmirror.com/vue-demi/-/vue-demi-0.14.10.tgz",