refactor: harden diagnostics and consolidate runtime code

audit/internal/webui/server.go

@@ -348,6 +348,7 @@ func NewHandler(opts HandlerOptions) http.Handler {
 	mux.HandleFunc("POST /api/system/install-to-ram", h.handleAPIInstallToRAM)
 	mux.HandleFunc("POST /api/system/reboot", h.handleAPISystemReboot)
 	mux.HandleFunc("POST /api/system/shutdown", h.handleAPISystemShutdown)
+	mux.HandleFunc("GET /api/system/time", h.handleAPISystemTime)
 	mux.HandleFunc("POST /api/system/time-sync", h.handleAPISystemTimeSync)
 
 	// Preflight
@@ -813,3 +814,19 @@ func writeError(w http.ResponseWriter, status int, msg string) {
 	w.WriteHeader(status)
 	_ = json.NewEncoder(w).Encode(map[string]string{"error": msg})
 }
+
+func writeAPIListResponse[T any](w http.ResponseWriter, configured bool, load func() ([]T, error)) {
+	if !configured {
+		writeError(w, http.StatusServiceUnavailable, "app not configured")
+		return
+	}
+	items, err := load()
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	if items == nil {
+		items = []T{}
+	}
+	writeJSON(w, items)
+}