fix: Sentinel 动态加载 chart.js + 空节点容错 + 默认为网格模式

plugins/sentinel/dashboard.html

@@ -1,4 +1,3 @@
-<script src="/SenSu/static/js/chart.js?v=0705"></script>
 <div class="plugin-page-root" style="padding:16px">
   <div style="display:flex;justify-content:space-between;align-items:center;margin-bottom:12px">
     <h2 style="margin:0">🛡️ Sentinel 集群监控</h2>
@@ -84,6 +83,13 @@
   </style>
 
   <script>
+    // 确保 chart.js 已加载 (SPA 导航时可能未加载)
+    if (typeof MiniChart === 'undefined') {
+      var cs = document.createElement('script');
+      cs.src = '/SenSu/static/js/chart.js?v=0705';
+      document.head.appendChild(cs);
+    }
+
     var pollTimer = null;
     var editingId = null;
     var _chartInstances = {};
@@ -293,8 +299,13 @@ card.querySelector('.node-time').innerHTML = '<div style="font-size:.7rem;color:
 
     function pollNodes() {
       fetch("/sentinel/api/nodes").then(function(r){return r.json()}).then(function(d){
-        if (d.nodes) renderNodes(d.nodes);
-      }).catch(function(){});
+        renderNodes(d.nodes || []);
+      }).catch(function(e){
+        var grid = document.getElementById("sentinel-grid");
+        if (grid && _firstRender) {
+          grid.innerHTML = '<div class="card" style="text-align:center;padding:24px;color:var(--error)">连接失败 — 检查节点配置</div>';
+        }
+      });
     }
 
     pollNodes();