Ticks taken while the OS reported no network were skipped, but they still
advanced the exponential backoff, so a peer could be tens of seconds from its
next attempt by the time connectivity returned. Recovery then depended on a
signal or relay event, which never arrives when both stayed up across the
outage, e.g. a short airplane mode toggle over Wi-Fi. A peer parked in ICE
hourly mode stayed there for the same reason.
React to the offline-to-online transition directly: re-arm the reconnect
ticker and reset the ICE retry state, so the peer retries at once. Add
netstate.Changed for callers that own a select loop and cannot block in Wait.
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