docs(site): add i18n type reference pages and review fixes

Add Locale, BuiltInLocale, TranslationParams, Translations, and Translator
reference pages plus createTranslator. Cross-link types from concept and
guides; fix React examples and register-locale satisfies pattern.

Co-authored-by: Cursor <cursoragent@cursor.com>

site/src/content/docs/reference/create-translator.mdx

@@ -0,0 +1,19 @@
+---
+title: createTranslator
+description: Build a typed translator from a resolved translation map
+---
+
+import UtilReference from "@/components/docs/api-reference/UtilReference.astro";
+import DocsLink from "@/components/docs/DocsLink.astro";
+
+`createTranslator` wraps a <DocsLink slug="reference/translations">`Translations`</DocsLink> map and returns a <DocsLink slug="reference/translator">`Translator`</DocsLink>. Providers call this internally after merging registry, lazy, and prop layers — use it directly for custom UI outside built-in mixins.
+
+```ts
+import { createTranslator, getI18nTranslations } from '@videojs/core/i18n';
+
+const t = createTranslator(getI18nTranslations('fr'), 'fr');
+t('play');
+t('seekForward', { seconds: 5 });
+```
+
+<UtilReference util="createTranslator" />