feat(i18n): restrict public routes and metadata to enabled locales

- Add ENABLED_LOCALES configuration in i18n/links.js (currently ["pt"])
- Redirect inactive locale prefixes to /pt via 307 in middleware.js
- Restrict root locale negotiation to active locales with fallback to pt
- Hide LanguageSelector when only one locale is enabled
- Generate sitemap, hreflang alternates, and og:locale only for active locales
- Generate static SSG pages only for active locales in build
- Adapt check:i18n and smoke-imagem.sh to validate active vs inactive locales

Co-Authored-By: Antigravity <noreply@google.com>

components/LanguageSelector.jsx

@@ -8,6 +8,10 @@ import { LOCALES, getLocalizedHref } from "@/i18n/links";
 export { LOCALES, getLocalizedHref };
 
 export default function LanguageSelector() {
+	if (LOCALES.length <= 1) {
+		return null;
+	}
+
 	const pathname = usePathname() || "";
 	const [open, setOpen] = useState(false);
 	const [hash, setHash] = useState("");