Event log: show attempt and delivery times, label replays, zone event times (closes #386)

Each attempt shows when it was recorded and each delivery when it was
created, in the event log and on the event's page. The event log's
event times read as the recent events list does: how long ago, with
the full UTC time on hover.

A delivery records whether Replay created it, in a new replay column
added to the delivery model in place. Such a delivery is labelled a
replay in the event's summary line and in both pages' delivery lists.

Model: opus-5-5

internal/handlers/event_log_view.go

@@ -3,6 +3,8 @@ package handlers
 import (
 	"time"
 	"unicode/utf8"
+
+	"github.com/dustin/go-humanize"
 )
 
 // eventLogColumns is the event log's projection. The casts to
@@ -28,10 +30,14 @@ const eventColumns = "id, created_at, method, content_type, " +
 // DeliveryView and TargetView.
 type EventLogView struct {
 	ID          string
-	CreatedAt   time.Time
 	Method      string
 	ContentType string
 
+	// Received is how long ago the event arrived, and ReceivedUTC
+	// the full timestamp.
+	Received    string
+	ReceivedUTC string
+
 	Body BodyView
 
 	// ResubmittedFromID names the event this one was copied
@@ -77,9 +83,10 @@ func (r *eventLogRow) view(webhookID string) EventLogView {
 
 	return EventLogView{
 		ID:          r.ID,
-		CreatedAt:   r.CreatedAt,
 		Method:      r.Method,
 		ContentType: r.ContentType,
+		Received:    humanize.Time(r.CreatedAt),
+		ReceivedUTC: r.CreatedAt.UTC().Format(time.DateTime) + " UTC",
 		Body: newBodyView(
 			"/hook/"+webhookID+"/events/"+r.ID, r.Body, r.BodyBytes,
 		),