Store and show an event's query string, and pass it on to an HTTP target when set (closes #312)

The receiver dropped the query string of every request it received, so a sender's URL parameters were silently lost. Each event now keeps it, as sent, in a new `raw_query` column of the per-webhook `events` table; a resubmitted copy carries its original's. The event log and the event's page show it in the shared request block, the event log leaving out one over 32 KiB with a link, as for headers. The archive and log targets carry it. HTTP targets gain "Pass the query string on to this target", off by default: on, deliveries, replays and resubmits append it to the target URL, joined with `&` to one already there. The access log still hides it.

Model: opus-5-5

internal/delivery/engine_integration_test.go

@@ -673,6 +673,11 @@ func TestRecoverPendingDeliveries(t *testing.T) {
 		t, s.WebhookDB, s.WebhookID, targetID, 3,
 	)
 
+	// A recovered delivery still carries its event's query string.
+	require.NoError(t, s.WebhookDB.Model(&database.Event{}).
+		Where("webhook_id = ?", s.WebhookID).
+		Update("raw_query", eventQuery).Error)
+
 	s.Engine.ExportRecoverPendingDeliveries(
 		context.Background(), s.WebhookDB,
 		s.WebhookID,
@@ -687,6 +692,8 @@ func TestRecoverPendingDeliveries(t *testing.T) {
 				database.TargetTypeLog,
 				task.TargetType,
 			)
+
+			assert.Equal(t, eventQuery, task.RawQuery)
 		case <-time.After(2 * time.Second):
 			t.Fatalf("expected task %d", i)
 		}