conservative static method

RetryConfig conservative()

预定义配置：保守重试（较长延迟，适合服务器过载）

Implementation

static RetryConfig conservative() {
  return RetryConfig(
    strategy: RetryStrategy.linear,
    maxAttempts: 3,
    initialDelay: const Duration(seconds: 3),
    maxDelay: const Duration(seconds: 30),
    enableJitter: true,
  );
}