fix(docs): keep the translated locale trees out of the search index (#662)

Search Console flagged four reasons on 2026-07-28: soft 404, both
duplicate-canonical variants, and noindex. All four sat on
docs.snapotter.com; the landing site was clean.

The cause was boilerplate dominance rather than a broken tag.
/tools/video/crop-video carries 1.3 KB of unique body against 3.5 KB of
identical chrome (nav, sidebar, 21-language switcher), so unrelated tool
docs measured 52-60% full-page similarity. Across 20 locales that was
3,640 of 3,822 submitted URLs. Google read the lot as one duplicate
cluster and began electing arbitrary representatives: /changelog became
the canonical for /tools/image/favicon, and /uk/guide/getting-started for
/nl/tools/image/resize. English tool docs indexed 2 of 10 and localized 4
of 10, while the landing page for those same five tools indexed 5 of 5.

Translated pages now emit `noindex, follow` with a self-canonical, and
sitemap.transformItems drops them from the sitemap. Self-canonical rather
than pointing at English, since noindex paired with a cross-canonical
sends two conflicting instructions. hreflang is removed outright: the
annotation only means something between pages that can all be indexed.

Readers see no change. The language switcher and every in-page link
behave exactly as before.

Verified against a real build: sitemap 3,822 to 182 URLs with zero
translated entries, all 3,640 translated files carrying the noindex and
no English file doing so, docs e2e 100 passed.

tests/e2e-docs/i18n.spec.ts

@@ -38,14 +38,21 @@ test.describe("docs i18n (English + committed German locale)", () => {
     await expect(target).toBeInViewport();
   });
 
-  test("hreflang alternates are reciprocal and include x-default", async ({ page }) => {
+  test("English pages are indexable and self-canonical", async ({ page }) => {
     await page.goto("/guide/getting-started");
-    const en = await page.locator('link[hreflang="en"]').getAttribute("href");
-    const de = await page.locator('link[hreflang="de"]').getAttribute("href");
-    const xd = await page.locator('link[hreflang="x-default"]').getAttribute("href");
-    expect(en).toContain("/guide/getting-started");
-    expect(de).toContain("/de/guide/getting-started");
-    expect(xd).toBe(en);
+    const canonical = await page.locator('link[rel="canonical"]').getAttribute("href");
+    expect(canonical).toBe("https://docs.snapotter.com/guide/getting-started");
+    await expect(page.locator('meta[name="robots"]')).toHaveCount(0);
+  });
+
+  // Only English is indexable, so there is no hreflang cluster left to annotate.
+  // See the transformHead comment in apps/docs/.vitepress/config.mts.
+  test("translated pages are noindex, self-canonical, and carry no hreflang", async ({ page }) => {
+    await page.goto("/de/guide/getting-started");
+    const canonical = await page.locator('link[rel="canonical"]').getAttribute("href");
+    expect(canonical).toBe("https://docs.snapotter.com/de/guide/getting-started");
+    await expect(page.locator('meta[name="robots"]')).toHaveAttribute("content", "noindex, follow");
+    await expect(page.locator("link[hreflang]")).toHaveCount(0);
   });
 
   test("pagefind returns results within the German locale", async ({ page }) => {

tests/unit/surface-playwright-harness.test.ts

@@ -267,7 +267,7 @@ test("docs Playwright collection includes explicit Axe coverage", () => {
   for (const pageName of ["homepage", "getting started", "configuration", "REST API"]) {
     expect(output).toContain(`${pageName} has no Axe violations`);
   }
-  expect(output).toContain("Total: 99 tests in 7 files");
+  expect(output).toContain("Total: 100 tests in 7 files");
 });
 
 test("Turbo passes surface harness overrides through task boundaries", () => {