seo: /v2 and /v2-5 canonical to the home and out of the sitemap

Superseded release pages that were taking two brand sitelink slots (5.9k
impressions, 29 clicks). They still render for old links; hreflang is
only emitted for a page that is its own canonical (prerender + useSEO).

frontend/public/sitemap.xml

@@ -87,16 +87,6 @@
     <changefreq>monthly</changefreq>
     <priority>0.85</priority>
   </url>
-  <url>
-    <loc>https://velxio.dev/v2/</loc>
-    <changefreq>monthly</changefreq>
-    <priority>0.9</priority>
-  </url>
-  <url>
-    <loc>https://velxio.dev/v2-5/</loc>
-    <changefreq>monthly</changefreq>
-    <priority>0.9</priority>
-  </url>
   <url>
     <loc>https://velxio.dev/v3/</loc>
     <changefreq>weekly</changefreq>

frontend/scripts/prerender-seo.mjs

@@ -147,7 +147,11 @@ try {
     } else {
       html = html.replace('</head>', `  ${canonicalTag}\n  </head>`);
     }
-    html = withHreflang(html, route.path);
+    // hreflang only for a page that is its own canonical; a page pointing
+    // its canonical elsewhere (/v2 -> /) must not declare alternates.
+    if (withSlash(seoMeta.url) === withSlash(`${DOMAIN}${route.path}`)) {
+      html = withHreflang(html, route.path);
+    }
 
     // Replace OG tags
     html = html.replace(

frontend/src/seoRoutes.ts

@@ -236,24 +236,31 @@ export const SEO_ROUTES: SeoRoute[] = [
   {
     path: '/v2',
     priority: 0.9,
+    // Superseded release page. Canonical points at the home (seoMeta.url)
+    // and noindex keeps it out of the sitemap: /v2 and /v2-5 were taking
+    // two brand sitelink slots (5.9k impressions, 29 clicks) that the
+    // editor and the simulator landings should hold. The page still
+    // renders for old links.
+    noindex: true,
     changefreq: 'monthly',
     seoMeta: {
       title: 'Velxio 2.0 — Multi-Board Embedded Simulator | ESP32, Raspberry Pi, Arduino, RISC-V',
       description:
         'Velxio 2.0 is here. Simulate Arduino, ESP32, Raspberry Pi Pico, and Raspberry Pi 3 in your browser. 19 boards, 68+ examples, realistic sensor simulation. Free and open-source.',
-      url: `${DOMAIN}/v2`,
+      url: `${DOMAIN}/`,
     },
   },
   {
     path: '/v2-5',
     priority: 0.9,
+    noindex: true, // see /v2
     changefreq: 'monthly',
     seoMeta: {
       title:
         'Velxio 2.5 — Arduino + SPICE Analog Circuit Simulator in Your Browser | ngspice-WASM',
       description:
         'Velxio 2.5 brings real-time analog circuit simulation via ngspice-WASM. Hybrid digital + analog co-simulation: resistors, capacitors, inductors, op-amps, transistors, voltmeters, ammeters — wired to Arduino, ESP32, RP2040 GPIO/ADC. 40+ circuit examples. Free and open-source.',
-      url: `${DOMAIN}/v2-5`,
+      url: `${DOMAIN}/`,
     },
   },
   {

frontend/src/utils/useSEO.ts

@@ -70,6 +70,13 @@ function localeLinks(url: string): { canonical: string; alternates: { hreflang:
     return { canonical: canonicalDefault, alternates: [] };
   }
   if (!isLocalizedRoute(strippedPath)) return { canonical: canonicalDefault, alternates: [] };
+  // A page whose canonical is another page (/v2 -> /) keeps that canonical
+  // as given and declares no alternates.
+  if (typeof window !== 'undefined') {
+    const herePath = stripLocaleFromPath(window.location.pathname).replace(/\/+$/, '') || '/';
+    const urlPath = strippedPath.replace(/\/+$/, '') || '/';
+    if (herePath !== urlPath) return { canonical: canonicalDefault, alternates: [] };
+  }
   const current = typeof window !== 'undefined' ? getLocaleFromPath(window.location.pathname) : DEFAULT_LOCALE;
   const variant = (l: (typeof LOCALES)[number]) => withTrailingSlash(`${DOMAIN}${localizedPath(strippedPath, l)}`);
   return {