Fix session timeout check with -t tokens

[Roadmaster]

This apparently broke on flyctl 0.3.210, probably went unnoticed since it's not a frequently used feature; user who reported it was stuck on 0.3.208.

With a freshly-generated token passed via -t:

$ fly -t "$FLY_ACCESS_TOKEN_NO_API" deploy
Welcome back!
Your session has expired, please log in to continue using flyctl.

? Would you like to sign in? No
Error: No access token available. Please login with 'flyctl auth login'

The 30-day session timeout feature has had a bumpy history:

1. 1f90b74 — "Introducing 30-day cli session timeout" (Introducing 30-day cli session timeout #4630, Nov 5 2025) — the original version had no bypass at all, meaning even env var tokens would hit the timeout.
2. 80affc2 — "Revert session timeout feature" (Revert session timeout feature due to test failures #4633) — reverted due to issues.
3. 5a396de — "session timeout-improved" (session timeout-improved #4645, Nov 10 2025) — reintroduced with an env var bypass for CI/CD, but missed the -t flag. This is the commit that introduced the bug the reporting user hit.

So the -t flag was never accounted for — it was an oversight in the improved version (#4645)
when the env var bypass was added.

This code applies the env var timeout bypass for a token passed via -t as well.