#949 moved the "token still valid -> return True" short-circuit in TidalClient.is_authenticated()
into the boot-phase branch ONLY, so after boot every call fell through to the silent refresh
regardless of whether the token was actually expired. With multiple workers polling Tidal every
few seconds, that produced a constant "access token expired -> refresh -> success" loop (wolf39us
logs) — needless token churn, not an actual auth problem.
Restored the valid-token short-circuit on the post-boot path. The download client is unaffected
(it defers the tidalapi session differently, no manual expiry loop).
3 regression tests: valid token post-boot does NOT refresh, expired token still does, valid token
during boot returns True without probing.
