feat(panel): adaptive monitoring poll intervals (v1.x closure phase 1)

Replace fixed 5 s hx-trigger polling with data-poll markers and panel.js
scheduling: 5 s while active, 30 s when idle, none when tab is hidden.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

internal/web/templates/deliveries_rows.html

@@ -1,6 +1,6 @@
 {{define "deliveries_rows"}}
-<div id="deliveries-rows" hx-get="/deliveries/rows?domain={{.FilterDomain}}&app={{.FilterApp}}&p={{.Page}}"
-     hx-trigger="every 5s" hx-swap="outerHTML">
+<div id="deliveries-rows" data-poll hx-get="/deliveries/rows?domain={{.FilterDomain}}&app={{.FilterApp}}&p={{.Page}}"
+     hx-trigger="load" hx-swap="outerHTML">
   {{if .Rows}}
   <table>
     <thead>