A failed /steer (or busy-mode steer) no longer silently falls back to interrupt+queue
(which cancelled the active stream). _trySteer now returns delivered:bool, restores the
draft + leaves the stream running on failure; send() only clears staged files when
_steerDelivered===true. Backend hunk comment-only (failure paths already returned
{accepted:False}, never touched CANCEL_FLAGS). i18n value-only on pre-existing keys
(locale-parity preserved, 173 locale tests pass). 48 own tests pass.
Co-authored-by: nesquena-hermes <agent@nesquena-hermes>
Co-authored-by: dso2ng <dso2ng@users.noreply.github.com>
