fix: make Alerts page scrollable

Override the global style.css body height/overflow that locks all pages
to the viewport height (a remnant of the old drawer-menu layout).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hbd/server/templates/alerts.html

@@ -4,6 +4,11 @@
 
   <style>
 
+    body {
+      height: auto;
+      overflow-y: auto;
+    }
+
     .container {
       max-width: 1400px;
       margin: 0 auto;