Add pagination to event queries, input validation, daily event purge

- get_active_events() now takes limit/offset (default 200) to cap unbounded queries
- count_active_events() added to return total for pagination display
- /api/events supports ?limit=, ?offset=, ?status= query params (max 1000)
- /api/status includes total_active count alongside paginated events list
- index() route passes total_active to template for server-side truncation notice
- Show "Showing X of Y" notice in dashboard when events are truncated
- Suppression POST validates: reason ≤500 chars, target_name/detail ≤255 chars
- _purge_old_jobs_loop runs purge_old_resolved_events(90d) once per day

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

static/app.js

@@ -22,7 +22,7 @@ async function refreshAll() {
 
     updateHostGrid(net.hosts || {});
     updateUnifiTable(net.unifi || []);
-    updateEventsTable(status.events || []);
+    updateEventsTable(status.events || [], status.total_active);
     updateStatusBar(status.summary || {}, status.last_check || '');
     updateTopology(net.hosts || {});
 
@@ -147,7 +147,7 @@ function updateUnifiTable(devices) {
   }).join('');
 }
 
-function updateEventsTable(events) {
+function updateEventsTable(events, totalActive) {
   const wrap = document.getElementById('events-table-wrap');
   if (!wrap) return;
 
@@ -157,6 +157,11 @@ function updateEventsTable(events) {
     return;
   }
 
+  const truncated = totalActive != null && totalActive > active.length;
+  const countNotice = truncated
+    ? `<div class="pagination-notice">Showing ${active.length} of ${totalActive} active alerts &mdash; <a href="/api/events?limit=1000">view all via API</a></div>`
+    : '';
+
   const rows = active.map(e => {
     const supType = e.event_type === 'unifi_device_offline' ? 'unifi_device'
                   : e.event_type === 'interface_down'       ? 'interface'
@@ -188,6 +193,7 @@ function updateEventsTable(events) {
   }).join('');
 
   wrap.innerHTML = `
+    ${countNotice}
     <div class="table-wrap">
       <table class="data-table" id="events-table">
         <thead>