ui: dashboard crit-alerts banner

web/templates/pages/dashboard.html

@@ -4,6 +4,7 @@
 <div class="max-w-[1280px] mx-auto px-8">
 
   {{$page := .Page}}
+  {{template "crit_banner" .Page}}
   {{if eq $page.HostCount 0}}
 
     {{/* ---------- empty state ---------- */}}

web/templates/partials/crit_banner.html

@@ -0,0 +1,13 @@
+{{define "crit_banner"}}
+{{if gt .CritOpenCount 0}}
+<div class="crit-banner flex items-center justify-between mb-4 px-4 py-2.5 rounded-md text-[13px]"
+     style="border: 1px solid color-mix(in oklch, var(--bad), transparent 60%);
+            background: color-mix(in oklch, var(--bad), transparent 88%);">
+  <div class="flex items-center gap-3">
+    <span class="dot dot-critical"></span>
+    <span><span class="text-bad font-medium">{{.CritOpenCount}} critical alert{{if ne .CritOpenCount 1}}s{{end}}</span> open across the fleet</span>
+  </div>
+  <a href="/alerts?severity=critical&status=open" class="btn btn-danger">Review →</a>
+</div>
+{{end}}
+{{end}}