fix(admin): system-status load-failed pairs alert with Retry button

When `/api/admin/status` 500s (rolling deploy, transient DB blip),
the section's error state previously rendered a static "refresh the
page" message — forcing a full reload + cookie revalidation just to
recover from a 5-second hiccup. Pairing the alert with an inline
Retry button (`refetch()` from React Query) lets the admin recover
in-place without losing scroll position or any other open admin tab.

The button is `min-h-9` desktop-tight (this is admin, not mobile-
critical), shows a spinner while `isFetching`, and disables itself
during the request. The German + English message strings drop the
"refresh the page" tail since the button now does that work.

messages/de.json

@@ -1436,7 +1436,8 @@
     "activeTokens": "Aktive API-Tokens",
     "activeSessions": "Aktive Sessions",
     "loadingStatus": "Lade Status...",
-    "systemStatusLoadError": "System-Status konnte nicht geladen werden. Bitte die Seite neu laden.",
+    "systemStatusLoadError": "System-Status konnte nicht geladen werden.",
+    "systemStatusRetry": "Erneut versuchen",
     "adminSettingsLoadError": "Admin-Einstellungen konnten nicht geladen werden. Schalter unten zeigen evtl. nicht den Live-Zustand — Seite neu laden.",
     "hostMetrics": {
       "title": "Host-Auslastung",

messages/en.json

@@ -1436,7 +1436,8 @@
     "activeTokens": "Active API Tokens",
     "activeSessions": "Active Sessions",
     "loadingStatus": "Loading status...",
-    "systemStatusLoadError": "Failed to load system status. Try refreshing the page.",
+    "systemStatusLoadError": "Failed to load system status.",
+    "systemStatusRetry": "Retry",
     "adminSettingsLoadError": "Failed to load admin settings. Toggles below may not reflect the live state — refresh the page.",
     "hostMetrics": {
       "title": "Host load",

src/components/admin/system-status-section.tsx

@@ -13,9 +13,11 @@ import {
   Globe,
   Key,
   Loader2,
+  RotateCw,
   Server,
   Users,
 } from "lucide-react";
+import { Button } from "@/components/ui/button";
 import { formatDateTime } from "@/lib/format";
 import { useFormatters, useTranslations } from "@/lib/i18n/context";
 import { StatusItem, useSystemStatus } from "./_shared";
@@ -41,7 +43,7 @@ const HostMetricsChart = dynamic(
 export function SystemStatusSection() {
   const { t } = useTranslations();
   const fmt = useFormatters();
-  const { data: status, isError } = useSystemStatus();
+  const { data: status, isError, refetch, isFetching } = useSystemStatus();
 
   return (
     <div className="space-y-6">
@@ -164,11 +166,30 @@ export function SystemStatusSection() {
         // P19: surface load failures inline instead of leaving the
         // section spinning forever. The hook throws on non-OK
         // responses, so isError is true on 500s, network errors, etc.
+        // v1.4.16 Wave-C MED — pair the alert with a Retry button so a
+        // transient 500 (rolling deploy, DB blip) doesn't require a
+        // full page reload to recover.
         <div
           role="alert"
-          className="text-destructive bg-destructive/10 border-destructive/30 mt-4 rounded-md border px-3 py-2 text-sm"
+          className="text-destructive bg-destructive/10 border-destructive/30 mt-4 flex flex-col items-start gap-2 rounded-md border px-3 py-2 text-sm sm:flex-row sm:items-center sm:justify-between"
         >
-          {t("admin.systemStatusLoadError")}
+          <span>{t("admin.systemStatusLoadError")}</span>
+          <Button
+            type="button"
+            size="sm"
+            variant="outline"
+            disabled={isFetching}
+            onClick={() => void refetch()}
+            className="min-h-9"
+            data-testid="system-status-retry"
+          >
+            {isFetching ? (
+              <Loader2 className="mr-1 h-3.5 w-3.5 animate-spin" />
+            ) : (
+              <RotateCw className="mr-1 h-3.5 w-3.5" />
+            )}
+            {t("admin.systemStatusRetry")}
+          </Button>
         </div>
       ) : (
         <div className="mt-4 flex items-center gap-2">