Show 50 recent events with size, processing time and status (closes #347)

The recent events list on a webhook's page now shows the 50 newest
events, each with its time relative to now (the full UTC timestamp on
hover), its body size, its processing time and, when the webhook has
exactly one HTTP target, that target's last HTTP status, colour-coded.
Resubmitted copies are marked, as in the event log.

Processing time is how long the event's slowest delivery took, from
being queued to its last recorded attempt. It is read from the existing
delivery and attempt timestamps, so nothing new is recorded. The body's
size is read in SQL, never the body.

Deliveries and attempts load in one batched query each, reusing the
event log's attempt loader.

Model: opus-5-5

templates/source_detail.html

@@ -187,12 +187,24 @@
         <div class="divide-y divide-gray-100">
             {{range .Events}}
             <div class="p-4">
-                <div class="flex items-center justify-between">
-                    <div class="flex items-center gap-3">
+                <div class="flex flex-wrap items-center justify-between gap-3">
+                    <div class="flex flex-wrap items-center gap-3">
                         <span class="badge-info">{{.Method}}</span>
-                        <span class="text-sm text-gray-500">{{.ContentType}}</span>
+                        <span class="text-sm text-gray-500 break-all">{{.ContentType}}</span>
+                        {{if .ResubmittedFromID}}
+                        <span class="text-xs text-gray-500" title="This event is a copy of {{.ResubmittedFromID}}">resubmitted copy</span>
+                        {{end}}
+                    </div>
+                    <div class="flex flex-wrap items-center gap-3 text-xs text-gray-400">
+                        <span title="Body size">{{.Size}}</span>
+                        {{if .ProcessingTime}}
+                        <span title="Processing time: how long the slowest delivery took, from being queued to its last attempt">{{.ProcessingTime}}</span>
+                        {{end}}
+                        {{if .Status}}
+                        <span class="font-medium {{.StatusClass}}" title="HTTP status from the HTTP target">{{.Status}}</span>
+                        {{end}}
+                        <span title="{{.ReceivedUTC}}">{{.Received}}</span>
                     </div>
-                    <span class="text-xs text-gray-400">{{.CreatedAt.Format "2006-01-02 15:04:05 UTC"}}</span>
                 </div>
             </div>
             {{else}}