Behaviour for deciding whether and when to retry a Bexio API request.

The default implementation is BexioApiClient.Req.RewriteDelay, which honors Bexio's ratelimit-reset header on 429 responses, retries transient server errors (408, 500, 502, 503, 504) and Req.TransportErrors, and emits telemetry for successes, errors, rate limits and retries.

Host applications can provide their own implementation by passing it as Req's :retry option, e.g.:

config :bexio_api_client, :req_options,
  retry: &MyApp.RetryPolicy.retry/2

Note that the token endpoint never uses this policy — refresh retry/backoff policy belongs to BexioApiClient.Req.AccessTokenRefresher.