fix: Sentinel 清除占位卡片 + 动画延长至 1s

plugins/sentinel/dashboard.html

@@ -87,7 +87,7 @@
     function animateValue(el, oldVal, newVal, decimals, suffix) {
       if (oldVal === newVal) { el.textContent = newVal.toFixed(decimals) + suffix; return; }
       var start = performance.now();
-      var duration = 350;
+      var duration = 1000;
       function step(ts) {
         var progress = Math.min((ts - start) / duration, 1);
         // ease-out
@@ -99,13 +99,18 @@
       requestAnimationFrame(step);
     }
 
+    var _firstRender = true;
+
     function renderNodes(nodes) {
       var grid = document.getElementById("sentinel-grid");
       if (!nodes.length) {
         grid.innerHTML = '<div class="card" style="text-align:center;padding:24px;color:var(--text-dim)">暂无节点 — 切换到节点管理添加</div>';
         _cardCache = {};
+        _firstRender = true;
         return;
       }
+      // 首次渲染清除占位
+      if (_firstRender) { grid.innerHTML = ''; _firstRender = false; }
       // 清理已删除的节点
       var activeIds = {};
       nodes.forEach(function(n){ activeIds[n.id||n.name] = true; });