fix(admin): move w_task_executions and w_schedules migrations to admin plugin

- Include w_schedules and w_task_executions DDL in admin initial migrations for both SQLite and PostgreSQL dialects
- Remove driver-specific migration registrations from driver_asynq_worker and driver_asynq_cron
- Fix missing table error when running in Zero-Redis standalone mode without Asynq
- Update white paper table ownership mapping and ensure test cleanup

backend/cmd/app_test.go

@@ -121,6 +121,7 @@ func TestNewWaveletAppWithRedisEnabled(t *testing.T) {
 	require.NotNil(t, app)
 	defer func() {
 		_ = app.Stop(context.Background())
+		_ = app.Context().Dispose()
 	}()
 	require.NoError(t, app.Reconcile())