agent-platform release v4.27.1

Fixed

• make verify-gpu-pool passes on a GOLDEN_REF that carries modelServing.gpuPool (#482). The untainted case asserts the serving render is byte-identical to GOLDEN_REF (origin/main by default) but for the discovery block — with the golden rendered at its own defaults. From the commit that merged #482 onto main that golden is tainted, so an untainted head could never equal it and test-ingress-modes failed on every branch cut from main, main included. The golden now takes the same modelServing.gpuPool.taint.key= override when its values.yaml declares the key, and the discovery block is cut from both sides: the assertion is that equal inputs render alike, which is what it was always meant to be. A golden from before #482 still renders at its defaults, unchanged.