feat(tickets): open, comment and resolve tickets from the UI and MCP; known issues on alerts and anomalies (#6351, #6352)

A ticket records a known problem: title, area, hosts, subject, description,
links to alert rules and anomalies, and a log of comments, edits, resolving
and reopening. Opening, resolving (with the resolution as the note) and
reopening go on the timeline; every step is audited, and the audit rows stay
off the timeline.

An alert or anomaly an open ticket covers (by link, by subject, or a
host-wide ticket on the host itself) shows a Known issue badge, and offers
"Open a ticket" prefilled from its rule or anomaly when none does. Hosts,
monitors and containers get a Known issues card.

MCP: list_tickets, get_ticket (viewer); open_ticket, update_ticket,
comment_ticket, resolve_ticket, reopen_ticket (operator). list_alerts and
list_anomalies carry known_issue; get_overview, get_host, get_monitor and
get_container carry open_tickets. Also update_change and delete_change for
changes recorded by hand (author or admin).

Tickets are left out of backups, like the timeline (2026-10-15 ruling).

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

steward/models/__init__.py

@@ -15,6 +15,7 @@ from .settings import AppSetting
 from .dashboard import Dashboard, DashboardWidget, DashboardShareToken
 from .outbox import EmailOutbox, email_outbox_events
 from .timeline import TimelineEntry
+from .tickets import Ticket, TicketLink, TicketNote
 
 __all__ = [
     "Base", "User", "ApiToken", "UserInvite", "PasswordReset",
@@ -29,4 +30,5 @@ __all__ = [
     "Dashboard", "DashboardWidget", "DashboardShareToken",
     "EmailOutbox", "email_outbox_events",
     "TimelineEntry",
+    "Ticket", "TicketLink", "TicketNote",
 ]