feat: implement i18n

frontend/src/core/i18n/hooks.ts

@@ -0,0 +1,57 @@
+"use client";
+
+import { useEffect, useState } from "react";
+
+import { enUS } from "./locales/en-US";
+import { zhCN } from "./locales/zh-CN";
+
+import { detectLocale, type Locale, type Translations } from "./index";
+
+const translations: Record<Locale, Translations> = {
+  "en-US": enUS,
+  "zh-CN": zhCN,
+};
+
+export function useI18n() {
+  const [locale, setLocale] = useState<Locale>(() => {
+    if (typeof window === "undefined") {
+      return "en-US";
+    }
+
+    // Try to get from localStorage first
+    const saved = localStorage.getItem("locale") as Locale | null;
+    if (saved && (saved === "en-US" || saved === "zh-CN")) {
+      return saved;
+    }
+
+    // Otherwise detect from browser
+    return detectLocale();
+  });
+
+  const t = translations[locale];
+
+  const changeLocale = (newLocale: Locale) => {
+    setLocale(newLocale);
+    if (typeof window !== "undefined") {
+      localStorage.setItem("locale", newLocale);
+    }
+  };
+
+  // Initialize locale on mount
+  useEffect(() => {
+    if (typeof window !== "undefined") {
+      const saved = localStorage.getItem("locale") as Locale | null;
+      if (!saved) {
+        const detected = detectLocale();
+        setLocale(detected);
+        localStorage.setItem("locale", detected);
+      }
+    }
+  }, []);
+
+  return {
+    locale,
+    t,
+    changeLocale,
+  };
+}