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/backup/contents.py

@@ -37,6 +37,9 @@ EXCLUDED: frozenset[str] = frozenset({
     "audit_events", "alert_events",
     # The timeline of what happened to the infrastructure: history.
     "timeline_entries",
+    # Tickets: a record of known problems and how they were worked, not
+    # setup. Left out like the timeline, by the 2026-10-15 ruling.
+    "tickets", "ticket_links", "ticket_notes",
     # Live state: each rule starts inactive, and alert_reconcile gives a
     # restored rule its state row within a minute (ensure_rule_states).
     "alert_states",