Jev adapter

The initial protocol helpers and their unit tests were extracted from the
System One extension in the local sglang-jev experiment, commit
633f05e (Add prefill-only System One decisions and visual game evaluation).
That repository was based on SGLang upstream commit
0024efa0de38794ee309ba10ab00ebb891a3d050.

The accompanying Apache License 2.0 is retained from that source tree.
SGLang project: https://github.com/sgl-project/sglang

This repository is an independent API adapter. It does not include the
proprietary Jev model and does not bundle the SGLang inference engine.

Benchmark metric definitions and dataset schema mapping follow Jared Palmer's
Apache-2.0 KEV project, pinned at 4f8110a3f8620cc3a182ae9a708e4398492c4b1a:
https://github.com/jaredpalmer/kev
The benchmark runner is an independent implementation. Downloaded benchmark
data retains upstream provenance and any underlying dataset license terms.