With BaseEnvironment supplying a backend-scoped probe to every production
caller, the module-level host-only `_sudo_nopasswd_works` (and its
TERMINAL_ENV gate) had no callers left; the `or` fallback and the outer
try/except around a callback that already fails closed were dead too.
Move the probe under `should_prompt_for_sudo`: headless callers (gateway,
cron, delegated children) reach `(command, None)` whether or not the probe
runs, so the extra backend round trip — an ssh exec on the SSH backend —
was pure waste on every headless sudo command.
test_subagent_sudo_prompt no longer needs to patch the host probe out:
bare `_transform_sudo_command(cmd)` calls have no probe by construction.
4fc64b6730