feat(m8): event-based alerts — Xid/OOM/MCE/PCIe/disk from the kernel log — 0.34.0

AlertMonitor now scans the kernel log (journalctl -k) every ~30s and fires
one-shot, cooldown-gated desktop alerts on critical events: NVIDIA Xid, OOM
kills, CPU machine-checks, PCIe AER, and disk I/O errors — so users are warned
the moment something goes wrong, not only on a temperature threshold. Disk I/O
errors come from the kernel log (no root needed, unlike smartctl). Edge/spam
protection reuses the existing cooldown model. syslogs.scan_critical() does the
matching; init seeds last-scan to "now" so old boot logs don't alert on launch.
Tests for the matcher + monitor gating/cooldown; Settings note updated.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_alerts.py

@@ -34,5 +34,35 @@ class AlertTests(unittest.TestCase):
         m.assert_called_once()
 
 
+class KernelEventAlertTests(unittest.TestCase):
+    @mock.patch.object(alerts, "notify")
+    def test_kernel_event_fires_once_within_cooldown(self, m):
+        mon = alerts.AlertMonitor(cooldown=300.0, event_interval=0.0)
+        mon._last_kernel_scan = 0.0  # force a scan
+        with mock.patch("rigdoctor.core.syslogs.kernel_log",
+                        return_value="NVRM: Xid (PCI:0000:01:00): 79, GPU has fallen off the bus"):
+            mon._scan_kernel_events()
+            mon._last_kernel_scan = 0.0  # force another scan — cooldown must suppress it
+            mon._scan_kernel_events()
+        self.assertEqual(m.call_count, 1)
+        self.assertIn("Xid", m.call_args[0][0])
+
+    @mock.patch.object(alerts, "notify")
+    def test_no_alert_when_kernel_log_empty(self, m):
+        mon = alerts.AlertMonitor(event_interval=0.0)
+        mon._last_kernel_scan = 0.0
+        with mock.patch("rigdoctor.core.syslogs.kernel_log", return_value=""):
+            mon._scan_kernel_events()
+        m.assert_not_called()
+
+    @mock.patch.object(alerts, "notify")
+    def test_scan_gated_by_interval(self, m):
+        mon = alerts.AlertMonitor(event_interval=9999.0)  # just constructed → not due yet
+        with mock.patch("rigdoctor.core.syslogs.kernel_log", return_value="NVRM: Xid 79") as kl:
+            mon._scan_kernel_events()
+        kl.assert_not_called()
+        m.assert_not_called()
+
+
 if __name__ == "__main__":
     unittest.main()