Show last run timestamp on ops automation status

Expose last_run_at / last_run on the status contract and display Last run
and Tasks columns on the /ops/ui status page for the selected window.

tests/test_automation_status.py

@@ -75,6 +75,28 @@ def test_completed_when_expected_run_exists() -> None:
     )
 
     assert report["status"] == "completed"
+    assert report["last_run_at"] == "2026-06-26T07:00:10+00:00"
+    assert report["last_run"]["run_id"] == "run-1"
+    assert report["last_run"]["tasks_spawned"] == 1
+
+
+def test_last_run_picks_newest_fired_at() -> None:
+    runs = [
+        {
+            "run_id": "older",
+            "fired_at": "2026-06-26T07:00:00+00:00",
+            "tasks_spawned": 0,
+        },
+        {
+            "run_id": "newer",
+            "fired_at": "2026-06-28T07:00:00+00:00",
+            "tasks_spawned": 2,
+        },
+    ]
+    summary = status.latest_run_summary(runs)
+    assert summary is not None
+    assert summary["run_id"] == "newer"
+    assert summary["tasks_spawned"] == 2
 
 
 def test_validation_failure_wins_over_completed_run() -> None: