feat: add localized home routes

src/languageRoutes.ts

@@ -0,0 +1,35 @@
+import type { Lang } from "./i18n";
+
+export const localizedHomeRoutes: ReadonlyArray<{ lang: Lang; path: string }> =
+  [
+    { lang: "zh-CN", path: "/chinese" },
+    { lang: "ja", path: "/japanese" },
+    { lang: "ko", path: "/korean" },
+    { lang: "vi", path: "/vietnamese" },
+    { lang: "id", path: "/indonesian" },
+    { lang: "ms", path: "/malay" },
+  ];
+
+function normalizePathname(pathname: string): string {
+  const normalized = pathname.replace(/\/+$/, "");
+  return normalized || "/";
+}
+
+export function languageForHomePathname(pathname: string): Lang | null {
+  const normalized = normalizePathname(pathname);
+  return (
+    localizedHomeRoutes.find((route) => route.path === normalized)?.lang ?? null
+  );
+}
+
+export function isHomePathname(pathname: string): boolean {
+  return (
+    normalizePathname(pathname) === "/" ||
+    languageForHomePathname(pathname) !== null
+  );
+}
+
+export function homePathForLang(lang: Lang): string {
+  if (lang === "en") return "/";
+  return localizedHomeRoutes.find((route) => route.lang === lang)?.path ?? "/";
+}