Add I18nProvider with useTranslation re-export for feature code

src/i18n/provider.tsx

@@ -0,0 +1,36 @@
+import {
+  I18nextProvider,
+  useTranslation as useTranslationOriginal,
+} from "react-i18next";
+import type { ReactNode } from "react";
+import type i18next from "i18next";
+
+/**
+ * Wraps the i18next provider. All downstream code accesses translations
+ * through this provider and the re-exported hooks below.
+ */
+export function I18nProvider({
+  i18n,
+  children,
+}: {
+  i18n: typeof i18next;
+  children: ReactNode;
+}): JSX.Element {
+  return <I18nextProvider i18n={i18n}>{children}</I18nextProvider>;
+}
+
+/**
+ * Re-export of react-i18next's useTranslation. Feature code MUST import
+ * from "@/i18n/provider", never from "react-i18next" directly (enforced
+ * by the no-restricted-imports ESLint rule in 1A-3).
+ */
+export const useTranslation = useTranslationOriginal;
+
+/**
+ * Convenience alias for accessing the i18next instance from context.
+ * Same as useTranslation().i18n.
+ */
+export function useI18n(): typeof i18next {
+  const { i18n } = useTranslation();
+  return i18n;
+}