Share async initialization

binder.bindAsyncLazySingleton<Database>(
  (resolver) => Database.open(resolver.get<AppConfig>().databasePath),
  dispose: (database) => database.close(),
);

Concurrent getAsync<Database>() calls await one in-flight Future. A successful result is retained; a failed attempt is cleared so a later call can retry. Use Async Factory instead when each caller genuinely needs a separate asynchronous object.