7dfa031d

By: Michael Lynch <git@mtlynch.io>

Return error from rate limiter Allow instead of bool

Change Limiter.Allow() to return nil when allowed or ErrLimitExceeded
when blocked, replacing the previous bool return. This lets callers
propagate the error directly instead of translating a bool into an
error at each call site.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>