fix(webui): translate MetricCard content

webui/tests/metric-card.test.tsx

@@ -0,0 +1,26 @@
+function assert(condition: unknown, message = "assertion failed"): void {
+  if (!condition) throw new Error(message);
+}
+
+import { renderToStaticMarkup } from "react-dom/server";
+import MetricCard from "../src/components/MetricCard";
+import { PlatformLanguageProvider } from "../src/i18n/LanguageContext";
+
+const translatedMarkup = renderToStaticMarkup(
+  <PlatformLanguageProvider>
+    <MetricCard
+      label="i18n:govoplan-core.installed_modules.32b3e799"
+      value="i18n:govoplan-core.core_only.d46ce7d9"
+      detail="i18n:govoplan-core.install_the_campaign_module_to_show_campaign_act.3085f23e"
+      tone="info"
+    />
+  </PlatformLanguageProvider>
+);
+
+assert(translatedMarkup.includes('class="metric-card metric-info"'), "the visual tone is preserved");
+assert(translatedMarkup.includes('class="metric-label">Installed modules</div>'), "the label is translated");
+assert(translatedMarkup.includes('class="metric-value">Core only</div>'), "a string value is translated");
+assert(!translatedMarkup.includes("i18n:govoplan-core."), "translation keys never leak into visible card text");
+
+const numericMarkup = renderToStaticMarkup(<MetricCard label="Count" value={7} />);
+assert(numericMarkup.includes('class="metric-value">7</div>'), "numeric values are preserved");