Name each database target's archive for its webhook and target (closes #376)

Each database target now has its own archive file,
archive-WEBHOOKNAME-TARGETNAME-TARGETID.db, instead of one
archive-WEBHOOKID.db per webhook. delivery.ArchiveFileName builds the
name: each name is lowercased, keeps ASCII letters and digits, turns
every other run of characters into one dash, and is cut to 40
characters.

Renaming a webhook or a target renames its archive files under the
archive writer's lock, before the new name is saved, and back again if
the save fails. Deleting a target evicts only that target's writer.
Archive files are never deleted, and nothing looks for files under the
old name.

Model: opus-5-5

internal/delivery/engine_test.go

@@ -351,23 +351,15 @@ func TestDeliverDatabase_ImmediateSuccess(
 
 	db := testWebhookDB(t)
 
-	// The database target archives for real now, so the engine
-	// needs a webhook DB manager to locate the data directory.
-	e := delivery.NewTestEngineWithDB(
-		nil,
-		database.NewTestWebhookDBManager(t.TempDir()),
-		slog.New(slog.NewTextHandler(
-			os.Stderr,
-			&slog.HandlerOptions{Level: slog.LevelDebug},
-		)),
-		&http.Client{Timeout: 5 * time.Second},
-		1,
-	)
+	// The database target archives for real, so the engine needs
+	// the target in the main database and a data directory.
+	env := setupArchiveTest(t)
+	tgt := env.seedDatabaseTarget(t, "")
 
 	event := seedEvent(t, db, `{"db":"target"}`)
-	d := seedDatabaseTargetDelivery(t, db, event, "")
+	d := seedDatabaseTargetDelivery(t, db, event, tgt)
 
-	e.ExportDeliverDatabase(db, d)
+	env.eng.ExportDeliverDatabase(db, d)
 
 	var updated database.Delivery
 
@@ -1336,32 +1328,27 @@ func TestProcessDelivery_RoutesToCorrectHandler(
 
 	db := testWebhookDB(t)
 
-	// The database target archives for real now, so the engine
-	// needs a webhook DB manager to locate the data directory.
-	e := delivery.NewTestEngineWithDB(
-		nil,
-		database.NewTestWebhookDBManager(t.TempDir()),
-		slog.New(slog.NewTextHandler(
-			os.Stderr,
-			&slog.HandlerOptions{Level: slog.LevelDebug},
-		)),
-		&http.Client{Timeout: 5 * time.Second},
-		1,
-	)
+	// The database target archives for real, so the engine needs
+	// the target in the main database and a data directory.
+	env := setupArchiveTest(t)
+	archive := env.seedDatabaseTarget(t, "")
 
 	tests := []struct {
 		name       string
 		targetType database.TargetType
+		targetID   string
 		wantStatus database.DeliveryStatus
 	}{
 		{
 			"database target",
 			database.TargetTypeDatabase,
+			archive.ID,
 			database.DeliveryStatusDelivered,
 		},
 		{
 			"log target",
 			database.TargetTypeLog,
+			uuid.New().String(),
 			database.DeliveryStatusDelivered,
 		},
 	}
@@ -1371,7 +1358,7 @@ func TestProcessDelivery_RoutesToCorrectHandler(
 			t.Parallel()
 
 			runRoutingSubtest(
-				t, db, e, tt.targetType,
+				t, db, env.eng, tt.targetType, tt.targetID,
 				tt.wantStatus,
 			)
 		})
@@ -1383,6 +1370,7 @@ func runRoutingSubtest(
 	db *gorm.DB,
 	e *delivery.Engine,
 	targetType database.TargetType,
+	targetID string,
 	wantStatus database.DeliveryStatus,
 ) {
 	t.Helper()
@@ -1390,8 +1378,7 @@ func runRoutingSubtest(
 	event := seedEvent(t, db, `{"routing":"test"}`)
 
 	dlv := seedDelivery(
-		t, db, event.ID,
-		uuid.New().String(),
+		t, db, event.ID, targetID,
 		database.DeliveryStatusPending,
 	)