Add continuous hardware health monitoring and component detail view

- kmsg watcher now records kernel errors (GPU Xid, MCE, EDAC, storage I/O) at all times,
  not only during SAT tasks; flushImmediate writes directly to ComponentStatusDB
- New health_poller: polls ipmitool sdr every 60s for PSU health (watchdog:psu source)
- Hardware Summary card auto-refreshes every 30s via htmx without page reload
- Component rows (CPU/Memory/Storage/GPU/PSU) are now clickable -- opens a modal
  with per-component status, source, timestamp and last 20 history entries

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

audit/internal/webui/kmsg_watcher.go

@@ -73,6 +73,9 @@ func (w *kmsgWatcher) run() {
 			w.mu.Lock()
 			if w.window != nil {
 				w.recordEvent(evt)
+			} else {
+				evtCopy := evt
+				goRecoverOnce("kmsg flush immediate", func() { w.flushImmediate(evtCopy) })
 			}
 			w.mu.Unlock()
 		}
@@ -180,6 +183,52 @@ func (w *kmsgWatcher) flushWindow(window *kmsgWindow) {
 	}
 }
 
+// flushImmediate writes a single kmsg event directly to the status DB without a SAT window.
+// Called when an error is detected outside of any SAT task (always-on watching).
+func (w *kmsgWatcher) flushImmediate(evt kmsgEvent) {
+	if w.statusDB == nil {
+		return
+	}
+	const source = "watchdog:kmsg"
+	detail := "kernel: " + truncate(evt.raw, 120)
+
+	var severity string
+	for _, p := range platform.HardwareErrorPatterns {
+		if p.Re.MatchString(evt.raw) {
+			if p.Severity == "critical" {
+				severity = "Critical"
+			} else {
+				severity = "Warning"
+			}
+			break
+		}
+	}
+	if severity == "" {
+		severity = "Warning"
+	}
+
+	if len(evt.ids) == 0 {
+		key := "cpu:all"
+		if evt.category == "memory" {
+			key = "memory:all"
+		}
+		w.statusDB.Record(key, source, severity, detail)
+		return
+	}
+	for _, id := range evt.ids {
+		var key string
+		switch evt.category {
+		case "gpu", "pcie":
+			key = "pcie:" + normalizeBDF(id)
+		case "storage":
+			key = "storage:" + id
+		default:
+			key = "pcie:" + normalizeBDF(id)
+		}
+		w.statusDB.Record(key, source, severity, detail)
+	}
+}
+
 // parseKmsgLine parses a single /dev/kmsg line and returns an event if it matches
 // any pattern in platform.HardwareErrorPatterns.
 // kmsg format: "<priority>,<sequence>,<timestamp_usec>,-;message text"