useSessionSync reloaded on any out-of-tab session change, so a routine
refresh in one tab hard-reloaded the others mid-call. Classify the
change: removed → reload, user/device changed → reload, same device with
a new token → swap it into the running client (setAccessToken + the
shared refresh token) in place. The refresher takes a Web Lock and adopts
tokens another tab already rotated instead of racing the issuer.
Unit-tested classifier.
Fixes#16
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA
