i18n: rename locale cookie to NEXT_LOCALE (Next.js convention)

src/modules/i18n/negotiateLocale.ts

@@ -3,7 +3,14 @@ import type { I18nConfig } from './types.js'
 import { getLocaleCodes, isValidLocale } from './helpers.js'
 
 /** Cookie name the template uses to persist a visitor's locale choice. */
-export const LOCALE_COOKIE_NAME = 'ipal-locale'
+/**
+ * Cookie name for the persisted locale choice. Uses NEXT_LOCALE — the convention
+ * Next.js and its i18n ecosystem expect — so the cookie is interoperable with
+ * other libraries that read the active locale (instead of a plugin-specific
+ * name). Written only under functional consent; cleared when that consent is
+ * withdrawn (see consent cookieMap).
+ */
+export const LOCALE_COOKIE_NAME = 'NEXT_LOCALE'
 
 type NegotiateLocaleArgs = {
   /** Raw Accept-Language header value */