Vendored isolation vectors for DOG-29 / DOG-22.

Canonical copy: barzoj-co/llmentary testdata/isolation/*.json
(proxy PR https://github.com/barzoj-co/llmentary/pull/35, merged to main
as bb39133; testdata/isolation/README.md is the spec note on main).

tests/test_isolation_vectors.py compares this directory to that path,
trying main first and then v{PROXY_VERSION}. CI fetches the same path
during the proxy-install step (one secret-bearing step). Missing access
is a visible skip; HTTP 404/403 after authenticating fails the check.
