Fix FreeBSD CI: set user to match CI runner for privilege check

Author: renaudallard

.github/workflows/freebsd.yml

@@ -70,10 +70,10 @@ jobs:
             test -f scripts/sniproxy.rc
 
             # Smoke test: start sniproxy with a test config
-            # cross-platform-actions runs as uid 1001 (runner), not root,
-            # so omit user directive (can't drop privileges without root)
+            # cross-platform-actions runs as user 'runner', not root
             echo "Running as: $(whoami) (uid=$(id -u))"
             printf '%s\n' \
+              "user $(whoami)" \
               'error_log { syslog daemon }' \
               'listener 127.0.0.1:18443 {' \
               '    protocol tls' \