Function retry_delay_secs

pub fn retry_delay_secs(config: RetryBackoffConfig, attempt: usize) -> i32

Computes retry delay in seconds from any backoff config + attempt.

Uses capped exponential backoff: initial_ms * 2^attempt, capped at max_ms. The exponent is clamped at 16 to avoid overflow, and the result is rounded up to whole seconds via div_ceil(1000).