fix(landing): link English-only tool-detail and self-hosted pages to un-prefixed URLs (#553)

Tool-detail pages (/tools/<section>/<tool>/) and the /self-hosted pages are
built only in English, with no per-locale route, so a locale-prefixed link
404s in the static build. Add an enOnlyHref() helper and use it for those
links in Footer, Navbar, HeroSearch, and ToolGrid so localized pages point at
the English pages that actually exist. Adds an e2e guard asserting localized
pages emit un-prefixed URLs for those routes.

tests/e2e-landing/en-only-links.spec.ts

@@ -0,0 +1,47 @@
+// tests/e2e-landing/en-only-links.spec.ts
+import { expect, test } from "@playwright/test";
+
+// Regression guard (QA sweep): tool-detail pages (/tools/<section>/<tool>/) and the
+// /self-hosted pages are built ONLY in English (no per-locale route). Localized pages
+// must therefore link to their UN-PREFIXED English URLs; a locale-prefixed link 404s in
+// the static build. We assert on the emitted href attributes (identical in dev and the
+// static build) so this catches the regression even though the webServer runs `astro dev`.
+const LOCALES = ["de", "ja"];
+
+async function collectHrefs(page: import("@playwright/test").Page): Promise<string[]> {
+  const anchors = await page.$$("a[href]");
+  const hrefs: string[] = [];
+  for (const a of anchors) hrefs.push((await a.getAttribute("href")) ?? "");
+  return hrefs;
+}
+
+for (const loc of LOCALES) {
+  test(`${loc}: English-only tool-detail & self-hosted links are not locale-prefixed`, async ({
+    page,
+  }) => {
+    const res = await page.goto(`/${loc}/`);
+    expect(res?.status()).toBeLessThan(400);
+
+    const hrefs = await collectHrefs(page);
+
+    // Tool-detail = /<loc>/tools/<section>/<tool>/ (two path segments after /tools/).
+    // The /<loc>/tools/ index and /<loc>/tools/<section>/ pages ARE localized and stay prefixed.
+    const toolDetailRe = new RegExp(`^/${loc}/tools/[^/]+/[^/]+/?$`);
+    const badToolDetail = hrefs.filter((h) => toolDetailRe.test(h));
+    expect(
+      badToolDetail,
+      `localized tool-detail links on /${loc}/ (must be un-prefixed /tools/...): ${badToolDetail.slice(0, 3).join(", ")}`,
+    ).toEqual([]);
+
+    // /self-hosted pages are English-only.
+    const badSelfHosted = hrefs.filter((h) => h.startsWith(`/${loc}/self-hosted`));
+    expect(
+      badSelfHosted,
+      `localized self-hosted links on /${loc}/: ${badSelfHosted.join(", ")}`,
+    ).toEqual([]);
+
+    // Sanity: the un-prefixed English tool-detail links are actually present (fix didn't drop them).
+    const enToolDetail = hrefs.filter((h) => /^\/tools\/[^/]+\/[^/]+\/?$/.test(h));
+    expect(enToolDetail.length).toBeGreaterThan(0);
+  });
+}