hive-claude adds its variables on top of the parent's environment, so
claude inherited the daemon's store identity paths, CREDENTIALS_DIRECTORY
and queue coordinates. claude now starts as this same binary with
SWARM_REVIEW_CLASSIFIER_EXEC_CLAUDE naming the real one; main execs it
before the runtime starts, with the environment cleared down to the API
key, PATH, HOME, CLAUDE_CONFIG_DIR and claude's telemetry settings. The
exec keeps the pid, so hive-claude's cancel and idle timeout still reach
it. An integration test runs the built binary as the trampoline and
checks that a BAO_* variable does not reach the program it execs.