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/api.go

@@ -1679,6 +1679,56 @@ func (h *handler) handleAPIBenchmarkResults(w http.ResponseWriter, r *http.Reque
 	fmt.Fprint(w, renderBenchmarkResultsCard(h.opts.ExportDir))
 }
 
+// ── Hardware summary / component detail ──────────────────────────────────────
+
+// handleAPIHardwareSummary returns the hardware summary card HTML fragment for
+// htmx polling (hx-get="/api/hardware-summary" hx-swap="outerHTML").
+func (h *handler) handleAPIHardwareSummary(w http.ResponseWriter, _ *http.Request) {
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	w.Header().Set("Cache-Control", "no-store")
+	fmt.Fprint(w, renderHardwareSummaryCard(h.opts))
+}
+
+// handleAPIComponentDetail returns an HTML fragment describing the current and
+// historical status for one component type (cpu, memory, storage, gpu, psu).
+func (h *handler) handleAPIComponentDetail(w http.ResponseWriter, r *http.Request) {
+	compType := r.PathValue("type")
+	var exact, prefixes []string
+	var title string
+	switch compType {
+	case "cpu":
+		title = "CPU"
+		exact = []string{"cpu:all"}
+	case "memory":
+		title = "Memory"
+		exact = []string{"memory:all"}
+		prefixes = []string{"memory:"}
+	case "storage":
+		title = "Storage"
+		exact = []string{"storage:all"}
+		prefixes = []string{"storage:"}
+	case "gpu":
+		title = "GPU"
+		prefixes = []string{"pcie:gpu:"}
+	case "psu":
+		title = "PSU"
+		prefixes = []string{"psu:"}
+	default:
+		http.NotFound(w, r)
+		return
+	}
+
+	var records []app.ComponentStatusRecord
+	if h.opts.App != nil && h.opts.App.StatusDB != nil {
+		all := h.opts.App.StatusDB.All()
+		records = matchedRecords(all, exact, prefixes)
+	}
+
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	w.Header().Set("Cache-Control", "no-store")
+	fmt.Fprint(w, renderComponentDetail(title, records))
+}
+
 func (h *handler) rollbackPendingNetworkChange() error {
 	h.pendingNetMu.Lock()
 	pnc := h.pendingNet