Point the sitemap, robots.txt and canonical links at the live domain

The www subdomain still serves the old site, so canonical and hreflang URLs now use
aigrowthtechnologies.com (overridable with SITE_URL). The sitemap also lists lastmod and changefreq.

src/app/sitemap.ts

@@ -13,10 +13,13 @@ export default function sitemap(): MetadataRoute.Sitemap {
     ...industryNav.map((s) => `/industries/${s.slug}`),
   ];
   const url = (p: string) => SITE_URL + (p === "/" ? "" : p);
+  const lastModified = new Date();
 
   return locales.flatMap((locale) =>
     paths.map((p) => ({
       url: url(localize(p, locale)),
+      lastModified,
+      changeFrequency: "monthly" as const,
       priority: p === "/" ? 1 : p.split("/").length === 2 ? 0.8 : 0.6,
       alternates: { languages: Object.fromEntries(locales.map((l) => [l, url(localize(p, l))])) },
     })),

src/lib/routes.ts

@@ -1,6 +1,8 @@
 // Route map and navigation. Kept free of page content so client components can import it.
 
-export const SITE_URL = "https://www.aigrowthtechnologies.com";
+// The live address used in canonical URLs, hreflang links, the sitemap and robots.txt.
+// Override with SITE_URL if the site moves to another host (for example the www subdomain).
+export const SITE_URL = (process.env.SITE_URL || "https://aigrowthtechnologies.com").replace(/\/$/, "");
 export const CONTACT_EMAIL = "info@aigrowthtechnologies.com";
 
 export const serviceNav = [