fix(docker): a crash-looping service belongs in Needs attention (#5209)

failing_services filtered on `(service_trouble(s) or 9) <= 2`; a crash loop
ranks 0, which is falsy, so the worst kind of trouble was left out. Test the
rank against None. The page test's task error also gains the age_s the
_swarm_failures include reads.

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

tests/plugins/docker/test_docker_page.py

@@ -117,7 +117,7 @@ async def test_a_failing_service_leads_and_the_failures_are_listed(app):
             "crash_looping": True, "failures_1h": 7, "failures_24h": 9, "tasks_known": True,
             "trouble_since": now - timedelta(minutes=20), "replicas": [], "previous_tasks": 7,
             "last_error": {"state": "failed", "error": "task: non-zero exit (1)", "exit_code": 1,
-                           "node": "nas", "at": None}}
+                           "node": "nas", "at": None, "age_s": 120}}
     failures = [{"kind": "service", "name": "codex_db", "host_id": None, "host": "nas", "count": 9,
                  "at": now - timedelta(minutes=2), "detail": "task: non-zero exit (1)"},
                 {"kind": "container", "name": "backup", "host_id": "h1", "host": "nas", "count": 1,