fix(transport): clamp FibonacciBackoff state at max to avoid u64 overflow - #770
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…flow `next_delay()` capped only the returned delay; the internal state kept growing as a raw Fibonacci sequence, which overflows u64 at call 93 (fib(94)). A reconnect loop with a large `max_reconnect_attempts` or `reconnect_forever` reaches that during a long outage. With the 30 s `max` both call sites use, about 45 minutes of continuous outage. In debug builds `next_delay()` would panic with `attempt to add with overflow`, and in release the addition would wrap and the delays would become nonsense.
- saturating_add covers max values above fib(93), where the raw sum overflows before the clamp engages - clamp current at construction so max=0 keeps meaning no delay instead of a fixed 1s
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The fix for PR #763 exposed an issue with
next_delay()that I didn't notice at the time.