feat(syslog): set-up help on the page, port 5514 published, Docker-hidden senders called out (#6003)

The Syslog page says where to send (this server, its port and protocols) and
where the setting is on Synology, QNAP, TrueNAS, OpenWrt, UniFi and rsyslog,
open until a device sends. A sender whose address is on Steward's own
container network (Swarm ingress publishing hides the real sender) is
flagged, with the host-mode ports to publish instead. compose files and the
Dockerfile publish 5514/udp and /tcp; docs/plugins/syslog.md describes the
plugin and the deploy.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Dockerfile

@@ -52,7 +52,7 @@ RUN useradd -m -u 1000 app \
     && mkdir -p /data/ansible/sources /data/ansible/runs /data/ansible/playbooks /data/plugins \
     && chown -R app:app /data /app
 
-EXPOSE 5000
+EXPOSE 5000 5514/udp 5514/tcp
 
 ENTRYPOINT ["/usr/bin/tini", "--", "/entrypoint.sh"]
 CMD ["steward", "--host", "0.0.0.0", "--port", "5000"]