feat(mcp): automation tools — playbooks, runs, schedules, alert actions, docker prune

MCP-6 #4970 "Automation tools: playbooks, runs, schedules, alert actions".

Viewer: list_playbooks, get_playbook (secret defaults masked), list_inventory
(variable names only), list_ansible_runs, get_ansible_run (log tail + grep),
list_schedules, wait_for_run (polls, 120s cap).

Operator: run_playbook (check mode unless check=false; a steward:confirm
playbook applies only with confirmed=true; secret variables reach the run
but are never stored, audited or returned), cancel_ansible_run, and
create/update/delete_schedule (secrets refused, check by default).

Admin: set_alert_action, and the docker plugin's prune_docker, which
previews from the disk report unless check=false (Ansible's check mode
skips the prune commands, so a check run would show nothing).

Every write is audited as "<user> via MCP" with the token id; the audit
tool's user filter includes those rows. prune_extra_vars moves to the
docker service so the page and the tool share it.

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

steward/mcp/tools/__init__.py

@@ -12,9 +12,9 @@ each argument's empty value means, and what comes back.
 """
 from __future__ import annotations
 
-from . import alerts, audit, hosts, metrics, monitors, overview, session
+from . import alerts, audit, automation, hosts, metrics, monitors, overview, session
 
-_MODULES = (session, overview, hosts, monitors, alerts, metrics, audit)
+_MODULES = (session, overview, hosts, monitors, alerts, metrics, audit, automation)
 
 
 def register_all(register_tool) -> None: