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/audit.py

@@ -3,11 +3,12 @@ from __future__ import annotations
 
 import json
 
-from sqlalchemy import select
+from sqlalchemy import or_, select
 
 from steward.models.audit import AuditEvent
 from steward.models.users import UserRole
 
+from ._audit import mcp_username
 from ._shape import age_s, bounded, clamp_limit, db_session, iso, lookback
 
 
@@ -17,7 +18,8 @@ async def list_audit_events(action: str = "", user: str = "", entity_type: str =
 
     action: a prefix of the action name, e.g. "monitor." or "ansible.run";
       empty for all.
-    user: a username, exactly; "system" for automated changes.
+    user: a username, exactly; "system" for automated changes. Includes the
+      changes that user made through MCP, which are recorded as "<user> via MCP".
     entity_type: e.g. "monitor", "host", "alert_rule"; empty for all.
     range: "1h", "6h", "24h", "7d" (default) or "30d".
     limit: default 50, max 500.
@@ -33,7 +35,8 @@ async def list_audit_events(action: str = "", user: str = "", entity_type: str =
         esc = action.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_")
         stmt = stmt.where(AuditEvent.action.like(esc + "%", escape="\\"))
     if user:
-        stmt = stmt.where(AuditEvent.username == user)
+        stmt = stmt.where(or_(AuditEvent.username == user,
+                              AuditEvent.username == mcp_username(user)))
     if entity_type:
         stmt = stmt.where(AuditEvent.entity_type == entity_type)
     async with db_session() as db: