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>

i18n/routing.js

@@ -1,8 +1,9 @@
 import { defineRouting } from "next-intl/routing";
+import { ENABLED_LOCALES } from "./links";
 
 export const routing = defineRouting({
-	locales: ["pt", "en", "es", "fr", "de", "zh-CN"],
-	defaultLocale: "en",
+	locales: ENABLED_LOCALES,
+	defaultLocale: ENABLED_LOCALES.includes("en") ? "en" : (ENABLED_LOCALES[0] || "pt"),
 	localePrefix: "always",
 	pathnames: {
 		"/": "/",