route.go gains Route.Affinity/Queue with PerRoute(), Queues() and affinity
validation (checkRoutes moved here; config.go calls it once). limiter.Track
counts a request without holding or refusing it; a release hands the slot to a
waiter only while in flight <= parallel. The proxy leases a PerRoute() route
under an empty fingerprint (the row keeps the real one) and uses Track when
Queues() is false.
Implemented by Ornith (OpenCode); owner review removed a release-on-first-flush
workaround for a race in the owner's given test (see implementer log).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
kyleandClaude Opus 5.5