backups: show that a check happened, not just that a change did

lastseenat already recorded it and the API already returned it; nothing
displayed it, so from the UI a healthy machine still looked abandoned - one
revision from last spring and no sign anything had looked at it since.

The history page gains a Last verified column beside Captured, and the asset
panel a Verified field. Only the CURRENT revision carries one: an older
revision was superseded, so saying it was verified today would be false - what
was verified is the configuration the PC holds now.

A current revision with no check yet says "not yet checked" rather than showing
a blank or borrowing the captured date. That state is real and temporary: the
column is new, so every chain reports it until its PC next posts.

tests/test_plugins/test_backups.py

@@ -960,3 +960,24 @@ def test_the_threshold_is_a_setting_and_zero_disables_the_card(bk_app, bk_plugin
             {'value': '0'})
         _db.session.commit()
         assert stalechains() == []
+
+
+def test_the_history_reports_when_a_config_was_last_verified(bk_app, bk_plugin):
+    """A machine checked daily for a year still shows one revision, because an
+    unchanged config writes none. The API has to say the check happened or that
+    machine reads as abandoned."""
+    from plugins.backups.models import BackupRevision
+    with bk_app.app_context():
+        result = bk_plugin.apply_collector_payload(_payload())
+        revision = _db.session.get(BackupRevision, result['backuprevisionid'])
+        data = revision.to_dict()
+        assert data['lastseenat'] is not None
+        assert data['lastseenat'].endswith('Z')
+
+
+def test_the_panel_shows_verified_beside_captured(bk_app, bk_plugin):
+    with bk_app.app_context():
+        panels = bk_plugin.get_asset_panels()
+        listpanel = next(p for p in panels if p.get('render') == 'list')
+        labels = [m['label'] for m in listpanel['map']['meta']]
+        assert 'Captured' in labels and 'Verified' in labels