feat(syslog): a source's lines to read and search, on its page, its host's and its SNMP device's, and over MCP (#6000)

- /plugins/syslog/sources/<id>: the lines newest first, loading as you
  scroll, filtered by severity and worse, app, text and time, with day
  dividers and times to the second in the reader's zone.
- The Syslog page links each source and shows its lines in the last hour.
- A Syslog panel on a host's page and an SNMP device's: the newest lines of
  the sources bound to it or at its address.
- MCP: list_syslog_sources and search_syslog (source, host, text, severity
  and worse, app, range, paging by next_before).
- Shared: escape_like moves to steward/core/like.py and cut_middle to the
  MCP shaping module, replacing four inline copies; |when takes seconds=.

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

steward/templates/hosts/detail.html

@@ -214,4 +214,9 @@
 <div hx-get="/plugins/snmp/host/{{ host.id }}" hx-trigger="load" hx-swap="innerHTML"></div>
 {% endif %}
 
+{# ── Syslog (renders nothing unless an added syslog source maps to this host) ── #}
+{% if "syslog" in enabled_plugins %}
+<div hx-get="/plugins/syslog/panel?host_id={{ host.id }}" hx-trigger="load" hx-swap="innerHTML"></div>
+{% endif %}
+
 {% endblock %}