Fix runtime default locale resolution

tests/metadata.test.ts

@@ -4,6 +4,7 @@ import { buildDefaultSiteSettings } from "../lib/site-settings";
 import {
   applyTitleTemplateFn,
   buildAppMetadataFromConfig,
+  buildLocaleAlternates,
   buildLocalizedMetadataFromConfig,
 } from "../lib/metadata";
 
@@ -96,4 +97,44 @@ describe("metadata helpers", () => {
 
     expect(metadata.title).toBe("اسم الموقع");
   });
+
+  it("builds alternates and canonical from the runtime default locale", () => {
+    const alternates = buildLocaleAlternates("/about", "ar");
+
+    expect(alternates.canonical).toBe("https://mohfarawati.de/about");
+    expect(alternates.languages.ar).toBe("https://mohfarawati.de/about");
+    expect(alternates.languages.de).toBe("https://mohfarawati.de/de/about");
+    expect(alternates.languages["x-default"]).toBe("https://mohfarawati.de/about");
+  });
+
+  it("builds localized metadata urls against the configured default locale", () => {
+    const settings = buildDefaultSiteSettings("Studio Moh");
+    settings.defaultLocale = "ar";
+
+    const metadata = buildLocalizedMetadataFromConfig({
+      settings,
+      bindings: {
+        siteLogoLight: null,
+        siteLogoDark: null,
+        favicon: null,
+        defaultOgImage: null,
+      },
+      locale: "de",
+      pathname: "/about",
+      title: "About",
+    });
+
+    expect(metadata.alternates).toMatchObject({
+      canonical: "https://mohfarawati.de/about",
+      languages: {
+        ar: "https://mohfarawati.de/about",
+        de: "https://mohfarawati.de/de/about",
+        en: "https://mohfarawati.de/en/about",
+        "x-default": "https://mohfarawati.de/about",
+      },
+    });
+    expect(metadata.openGraph).toMatchObject({
+      url: "https://mohfarawati.de/de/about",
+    });
+  });
 });