Follow-up for the salvaged #29239: regression test drives the real
gateway _reload_runtime_env_preserving_config_authority() path with a
stale .env TERMINAL_ENV=docker vs config.yaml terminal.backend=local,
and the hermes debug dump test that pinned the old stale-env-wins
symptom now pins the fixed contract (config wins, override line kept
as defense-in-depth for post-load env mutation).
Verifies `hermes debug` surfaces a TERMINAL_ENV override of
terminal.backend, reports the config value when no override is present,
and emits no spurious note when env and config agree.