v0.28.1 — portable TestHealth auth assertion
Patch on 0.28.0.
The TestHealth auth assertion introduced in 0.28.0 hardcoded /echo_int, which is correct only for a runner mounting RPC at the root. Ports that mount under a prefix and route before authenticating (Go) returned 404 there, failing the shared suite.
It now probes both candidate layouts and requires that neither is served unauthenticated and that the real endpoint refuses — meaningful on ports that authenticate before routing and on those that route first, without adding a per-runner fixture.