feat(alerts): Steward's own confirm dialog, a verdict-first rules list, and a rule page in three sections (#5314, #5315, #5317)

Confirm dialog (#5314):
- Every data-confirm form now asks in one native <dialog> (base.html + static/confirm.js)
  instead of window.confirm.
- The question becomes the heading and what follows it the detail; the act's
  button is named after the form's own button; Cancel has the focus and Esc
  backs out. Optional data-confirm-title/-detail/-action/-dismiss attributes.
- All 27 existing uses work as they are. Cancelling a run says 'Keep running'.

Alerts list (#5315):
- A verdict line (what is firing, how many rules, where notifications go,
  or 'notifies nobody yet' with a link) replaces the empty Active card.
- Each rule's name opens it; rows show 'last fired' and fold fire/clear into
  the condition; History and Disable stay; Delete leaves the list.
- .docker-verdict becomes the shared .page-verdict.

Rule page (#5317):
- Named for the rule (title and crumb), with when it last fired and how many
  changes of state it holds.
- Three sections: what it watches, when it fires (checks side by side,
  seconds echoed as a duration), what happens (where notifications go, no-data,
  the playbook, whose fields stay folded until ticked).
- Delete at the foot, behind the dialog, saying its history goes with it.

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

steward/alerts/service.py

@@ -251,6 +251,34 @@ async def active_count(db) -> int:
     )).scalar_one()
 
 
+def notify_targets(smtp: dict, webhook: dict) -> list[str]:
+    """Where an alert's notifications go, in words, by the same tests
+    core.notifications.dispatch_notifications sends by: email when a server
+    and recipients are set, a webhook when its URL is. Empty: nobody (#5315)."""
+    from urllib.parse import urlsplit
+    out = []
+    recipients = smtp.get("recipients") or []
+    if isinstance(recipients, str):
+        recipients = [r.strip() for r in recipients.split(",") if r.strip()]
+    if smtp.get("host") and recipients:
+        out.append("email to " + ", ".join(recipients))
+    if url := webhook.get("url"):
+        out.append("a webhook to " + (urlsplit(url).hostname or url))
+    return out
+
+
+async def last_fired(db, rule_id: str | None = None) -> dict[str, datetime]:
+    """{rule id: when it last went to firing}, for the rules that ever have;
+    one rule's when `rule_id` is given."""
+    stmt = (select(AlertEvent.rule_id, func.max(AlertEvent.transitioned_at))
+            .where(AlertEvent.to_state == AlertStateEnum.firing.value)
+            .group_by(AlertEvent.rule_id))
+    if rule_id:
+        stmt = stmt.where(AlertEvent.rule_id == rule_id)
+    rows = await db.execute(stmt)
+    return {rid: at for rid, at in rows.all()}
+
+
 async def list_rules(db) -> list[AlertRule]:
     return list((await db.execute(select(AlertRule).order_by(AlertRule.name))).scalars())