fix(seo): generate correct sitemap URLs for default locale

Sitemap was generating /en/* URLs which redirect to unprefixed paths
due to localePrefix: 'as-needed', causing Google Search Console
"Page with redirect" warnings and wasting crawl budget.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/app/sitemap.ts

@@ -5,6 +5,13 @@ const BASE_URL =
   process.env.NEXT_PUBLIC_APP_URL || 'https://skills.palebluedot.live';
 
 const locales = ['en', 'fa'] as const;
+const DEFAULT_LOCALE = 'en';
+
+/** Get canonical URL path for a locale (no prefix for default locale, matching localePrefix: 'as-needed') */
+function canonicalPath(locale: string, route: string): string {
+  if (locale === DEFAULT_LOCALE) return route || '/';
+  return `/${locale}${route}`;
+}
 
 const staticRoutes = [
   '',
@@ -27,7 +34,8 @@ const staticRoutes = [
 ];
 
 function makeEntry(
-  path: string,
+  locale: string,
+  route: string,
   options?: {
     lastModified?: Date;
     changeFrequency?: MetadataRoute.Sitemap[number]['changeFrequency'];
@@ -35,17 +43,13 @@ function makeEntry(
   }
 ): MetadataRoute.Sitemap[number] {
   return {
-    url: `${BASE_URL}${path}`,
+    url: `${BASE_URL}${canonicalPath(locale, route)}`,
     lastModified: options?.lastModified,
     changeFrequency: options?.changeFrequency,
     priority: options?.priority,
     alternates: {
       languages: Object.fromEntries(
-        locales.map((locale) => {
-          // For root path, use /en or /fa; for others, prefix with locale
-          const localePath = path.replace(/^\/(en|fa)/, `/${locale}`);
-          return [locale, `${BASE_URL}${localePath}`];
-        })
+        locales.map((l) => [l, `${BASE_URL}${canonicalPath(l, route)}`])
       ),
     },
   };
@@ -64,10 +68,9 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
   // Static pages (for each locale)
   for (const locale of locales) {
     for (const route of staticRoutes) {
-      const path = `/${locale}${route}`;
       const isHome = route === '';
       entries.push(
-        makeEntry(path, {
+        makeEntry(locale, route, {
           changeFrequency: isHome ? 'daily' : 'weekly',
           priority: isHome ? 1.0 : 0.5,
         })
@@ -82,7 +85,7 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
     for (const skill of allSkills) {
       for (const locale of locales) {
         entries.push(
-          makeEntry(`/${locale}/skill/${skill.id}`, {
+          makeEntry(locale, `/skill/${skill.id}`, {
             lastModified: skill.updatedAt,
             changeFrequency: 'weekly',
             priority: 0.7,
@@ -103,7 +106,7 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
     for (const [owner, lastModified] of uniqueOwners) {
       for (const locale of locales) {
         entries.push(
-          makeEntry(`/${locale}/owner/${owner}`, {
+          makeEntry(locale, `/owner/${owner}`, {
             lastModified,
             changeFrequency: 'weekly',
             priority: 0.6,
@@ -121,7 +124,7 @@ export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
     for (const category of allCategories) {
       for (const locale of locales) {
         entries.push(
-          makeEntry(`/${locale}/browse?category=${category.slug}`, {
+          makeEntry(locale, `/browse?category=${category.slug}`, {
             changeFrequency: 'weekly',
             priority: 0.5,
           })