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>

plugins/syslog/routes.py

@@ -19,6 +19,7 @@ from steward.models.metrics import PluginMetricLatest
 from steward.models.users import UserRole
 
 from .models import SyslogLine, SyslogPattern, SyslogSource
+from .network import on_own_network
 from .parse import SEVERITIES, facility_name, severity_name
 from .patterns import (PRESETS, PRESETS_BY_KEY, SOURCE_MODULE, WINDOWS, PatternError, key_for, parse_form,
                        resource_of)
@@ -55,6 +56,7 @@ def listener_view(port: int, udp: bool, tcp: bool) -> dict:
 def source_view(s: SyslogSource, hosts: dict, rate: int | None = None) -> dict:
     host = hosts.get(s.host_id) if s.host_id else None
     return {"id": s.id, "address": s.address, "state": s.state, "rate": rate,
+            "docker_address": on_own_network(s.address),
             "name": s.name or s.hostname_seen or s.address,
             "hostname_seen": s.hostname_seen, "host": host,
             "first_seen_at": s.first_seen_at, "last_seen_at": s.last_seen_at,
@@ -89,6 +91,7 @@ async def index():
     return await render_template("syslog/index.html", listener=listener,
                                  sources=views["accepted"], offered=views["offered"],
                                  ignored=views["ignored"], hosts=hosts,
+                                 server=request.host.rsplit(":", 1)[0] if request.host.count(":") == 1 else request.host,
                                  now=datetime.now(timezone.utc))