feat: configurable localePrefix via NEXT_PUBLIC_LOCALE_PREFIX

Allow the next-intl localePrefix mode to be set via environment
variable at build time, defaulting to the existing 'never' behavior.

This is useful when proxying Bulwark under a sub-path (where
'never' can trigger rewrite loops) or when users prefer
URL-embedded locales (/en/settings vs /settings).

Usage:
  NEXT_PUBLIC_LOCALE_PREFIX=always npm run build

Accepted values: 'never' (default), 'always', 'as-needed'.

i18n/routing.ts

@@ -1,9 +1,21 @@
 import { defineRouting } from 'next-intl/routing';
 
+// Locale prefix mode can be configured via NEXT_PUBLIC_LOCALE_PREFIX.
+// - "never"    (default): /settings — locale from cookie/Accept-Language
+// - "always":             /en/settings — locale always in the URL
+// - "as-needed":          /settings for default locale, /fr/settings otherwise
+// When proxying Bulwark under a sub-path (NEXT_PUBLIC_BASE_PATH), "always" is
+// recommended to avoid next-intl rewrite loops caused by locale detection
+// conflicting with the proxy's path rewriting.
+const localePrefix = (process.env.NEXT_PUBLIC_LOCALE_PREFIX ?? 'never') as
+  | 'never'
+  | 'always'
+  | 'as-needed';
+
 export const routing = defineRouting({
   locales: ['en', 'fr', 'de', 'es', 'it', 'ja', 'ko', 'lv', 'nl', 'pl', 'pt', 'ru', 'uk', 'zh'],
   defaultLocale: 'en',
-  localePrefix: 'never'
+  localePrefix
 });
 
 export const locales = routing.locales;