feat(i18n): add Japanese localization

src/components/settings-page.tsx

@@ -139,7 +139,7 @@ export function SettingsPage({
           setActiveSection(section);
           document.getElementById(sectionId)?.scrollIntoView?.({ block: "start", behavior: "smooth" });
         }}
-        className={`whitespace-nowrap rounded-md px-3 py-2 text-left text-sm font-medium transition-colors focus:outline-none focus:ring-2 focus:ring-indigo-500 focus:ring-offset-2 focus:ring-offset-background ${
+        className={`min-w-0 whitespace-normal break-words rounded-md px-3 py-2 text-left text-sm font-medium transition-colors focus:outline-none focus:ring-2 focus:ring-indigo-500 focus:ring-offset-2 focus:ring-offset-background ${
           selected
             ? "bg-indigo-600 text-white shadow-sm"
             : "text-muted-foreground hover:bg-muted hover:text-foreground"
@@ -174,6 +174,7 @@ export function SettingsPage({
                 <SelectContent>
                   <SelectItem value="en">{t("settings.lang_en")}</SelectItem>
                   <SelectItem value="zh">{t("settings.lang_zh")}</SelectItem>
+                  <SelectItem value="ja">{t("settings.lang_ja")}</SelectItem>
                 </SelectContent>
               </Select>
             </div>

src/i18n.ts

@@ -2,12 +2,13 @@ import i18n from "i18next";
 import { initReactI18next } from "react-i18next";
 import en from "./locales/en.json";
 import zh from "./locales/zh.json";
+import ja from "./locales/ja.json";
 
 // Initialize language from localStorage or navigator language
 const getInitialLanguage = (): string => {
   try {
     const saved = localStorage.getItem("language");
-    if (saved === "zh" || saved === "en") {
+    if (saved === "zh" || saved === "ja" || saved === "en") {
       return saved;
     }
   } catch (e) {
@@ -19,6 +20,9 @@ const getInitialLanguage = (): string => {
   if (browserLang.toLowerCase().includes("zh")) {
     return "zh";
   }
+  if (browserLang.toLowerCase().startsWith("ja")) {
+    return "ja";
+  }
   return "en";
 };
 
@@ -28,6 +32,7 @@ void i18n
     resources: {
       en: { translation: en },
       zh: { translation: zh },
+      ja: { translation: ja },
     },
     lng: getInitialLanguage(),
     fallbackLng: "en",

src/locales/en.json

@@ -68,6 +68,7 @@
     "title": "Codex Token Usage",
     "subtitle": "Local developer token tracking and cost estimator.",
     "last_updated": "Last updated {{time}}",
+    "updated_today": "Today at {{time}}",
     "last_updated_never": "Never updated",
     "rescan_duration": "Rescan completed in {{duration}}",
     "refresh": "Refresh",
@@ -586,6 +587,7 @@
     "language_label": "App Language",
     "lang_en": "English",
     "lang_zh": "简体中文",
+    "lang_ja": "日本語",
     "menu_bar_title": "Menu Bar / System Tray Settings",
     "menu_bar_desc": "Configure metrics for the macOS menu bar title, Windows tray tooltip, and tray menu.",
     "menu_bar_show_title": "Show in Menu Bar / Tray Tooltip",