feat: build an AI agent from 0 to 1 -- 11 progressive sessions

- 11 sessions from basic agent loop to autonomous teams
- Python MVP implementations for each session
- Mental-model-first docs in en/zh/ja
- Interactive web platform with step-through visualizations
- Incremental architecture: each session adds one mechanism

web/src/lib/i18n.tsx

@@ -0,0 +1,36 @@
+"use client";
+import { createContext, useContext, ReactNode } from "react";
+import en from "@/i18n/messages/en.json";
+import zh from "@/i18n/messages/zh.json";
+import ja from "@/i18n/messages/ja.json";
+
+type Messages = typeof en;
+
+const messagesMap: Record<string, Messages> = { en, zh, ja };
+
+const I18nContext = createContext<{ locale: string; messages: Messages }>({
+  locale: "en",
+  messages: en,
+});
+
+export function I18nProvider({ locale, children }: { locale: string; children: ReactNode }) {
+  const messages = messagesMap[locale] || en;
+  return (
+    <I18nContext.Provider value={{ locale, messages }}>
+      {children}
+    </I18nContext.Provider>
+  );
+}
+
+export function useTranslations(namespace?: string) {
+  const { messages } = useContext(I18nContext);
+  return (key: string) => {
+    const ns = namespace ? (messages as any)[namespace] : messages;
+    if (!ns) return key;
+    return (ns as any)[key] || key;
+  };
+}
+
+export function useLocale() {
+  return useContext(I18nContext).locale;
+}