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>

tests/plugins/docker/test_routes.py

@@ -41,17 +41,6 @@ def test_container_log_views_defined():
     assert callable(r.container_logs_lines)
 
 
-def test_prune_extra_vars_mapping():
-    """The prune buttons drive one playbook via prune_target; only 'images'
-    widens to ALL unused images (docker image prune -a), system stays -f."""
-    assert r._prune_extra_vars("containers") == {"prune_target": "containers"}
-    assert r._prune_extra_vars("images") == {
-        "prune_target": "images", "prune_all_images": True,
-    }
-    # System prune stays conservative — no prune_all_images key.
-    assert r._prune_extra_vars("system") == {"prune_target": "system"}
-
-
 def test_human_bytes_formats_binary_units():
     assert r._human_bytes(None) == "—"
     assert r._human_bytes(0) == "0 B"