fix(llm, openai): Stop a redeemed usage reset locking the account out

[JeanMertz]

A turn that spends a reset credit now keeps trying for up to a minute
while the redemption reaches the responses host, instead of retrying
once and abandoning the turn. The account confirms a redemption before
the host honours it, so that single immediate retry almost always
landed in the gap: the credit was spent, the reset applied, and the
turn ended anyway with Rate limited.

Attempts go out every five seconds until the request is admitted. The
credit is spent by then and the turn is unfinished, so waiting is what
the user paid for; each attempt is an admission-stage rejection that
bills nothing. Exactly one credit is spent however long the wait runs.

The wait is bounded because the other explanation for the refusal — a
usage window the credit does not cover — looks identical from here and
never resolves. When the budget runs out the turn falls through to the
rest of the chain as before.