Show each target's delivered and failed deliveries in the target list (closes #372)

The target list showed nothing about how a target's deliveries were going. Each target now shows Delivered and Failed, each in total and in the last 24 hours. The totals are the per-target running totals kept for the statistics pane, so retention does not reduce them; the 24-hour figures are one count over the deliveries' final-status index, for all of the webhook's targets at once. Pending and retrying deliveries count in neither. If the event database cannot be read, each row says so instead of showing zeros. The archive details and Download button on database targets are kept.

Model: opus-5-5

internal/server/routes_test.go

@@ -11,6 +11,7 @@ import (
 	"strconv"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
@@ -439,7 +440,8 @@ func (e *testEnv) storedEntrypoint(
 }
 
 // seedFailedDelivery records a terminally failed delivery of an event
-// to a target in the webhook's own database.
+// to a target in the webhook's own database, as the delivery engine
+// leaves one: finished now, and counted in its target's totals.
 func (e *testEnv) seedFailedDelivery(
 	t *testing.T,
 	webhookID, eventID, targetID string,
@@ -449,16 +451,21 @@ func (e *testEnv) seedFailedDelivery(
 	webhookDB, err := e.dbMgr.GetDB(webhookID)
 	require.NoError(t, err)
 
+	finishedAt := time.Now()
 	dlv := &database.Delivery{
-		EventID:  eventID,
-		TargetID: targetID,
-		Status:   database.DeliveryStatusFailed,
+		EventID:    eventID,
+		TargetID:   targetID,
+		Status:     database.DeliveryStatusFailed,
+		FinishedAt: &finishedAt,
 	}
 
 	require.NoError(
 		t,
 		webhookDB.Omit(clause.Associations).Create(dlv).Error,
 	)
+	require.NoError(t, database.AddTargetTotals(webhookDB,
+		database.TargetTotals{TargetID: targetID, Deliveries: 1, Failed: 1},
+	))
 
 	return dlv
 }