The identity fingerprint no longer includes token ids: guards decide on
scopes, subjects and the ceiling, and an OAuth access token's id changes on
every refresh, so a rotation alone no longer re-filters a cached server.
The stateless path's refresh only adds tools and prompts for a fingerprint
new to the entry (remembered until a fan-out recompute) and never removes:
one server serves every live token of a binding, and removing on each
alternation between a wider and a narrower token pulled a tool from under
the wider token's call. The receiving middleware still filters every list
and call per request; fan-out recomputes still narrow. The stateful path
keeps its exact widen, a session serves one client.
TestFingerprintIgnoresTokenID pins the fingerprint; TestStatelessSharedBinding
blocks the wide token's call after its server was chosen, sends a request
of the narrow token and asserts the call still succeeds (it failed with
"unknown tool" before).
