Add documents site (#1767)

* feat: add docs site

- Implemented dynamic routing for MDX documentation pages with language support.
- Created layout components for documentation with a header and footer.
- Added metadata for various documentation sections in English and Chinese.
- Developed initial content for the DeerFlow App and Harness documentation.
- Introduced i18n hooks and translations for English and Chinese languages.
- Enhanced header component to include navigation links for documentation and blog.
- Established a structure for tutorials and reference materials.
- Created a new translations file to manage locale-specific strings.

* feat: enhance documentation structure and content for application and harness sections

* feat: update .gitignore to include .playwright-mcp and remove obsolete Playwright YAML file

* fix(docs): correct punctuation and formatting in documentation files

* feat(docs): remove outdated index.mdx file from documentation

* fix(docs): update documentation links and improve Chinese description in index.mdx

* fix(docs): update title in Chinese for meta information in _meta.ts

frontend/src/core/i18n/hooks.ts

@@ -4,22 +4,15 @@ import { useEffect } from "react";
 
 import { useI18nContext } from "./context";
 import { getLocaleFromCookie, setLocaleInCookie } from "./cookies";
-import { enUS } from "./locales/en-US";
-import { zhCN } from "./locales/zh-CN";
+import { translations } from "./translations";
 
 import {
   DEFAULT_LOCALE,
   detectLocale,
   normalizeLocale,
   type Locale,
-  type Translations,
 } from "./index";
 
-const translations: Record<Locale, Translations> = {
-  "en-US": enUS,
-  "zh-CN": zhCN,
-};
-
 export function useI18n() {
   const { locale, setLocale } = useI18nContext();
 

frontend/src/core/i18n/locale.ts

@@ -6,6 +6,16 @@ export function isLocale(value: string): value is Locale {
   return (SUPPORTED_LOCALES as readonly string[]).includes(value);
 }
 
+export function getLocaleByLang(lang: string): Locale {
+  const normalizedLang = lang.toLowerCase();
+  for (const locale of SUPPORTED_LOCALES) {
+    if (locale.startsWith(normalizedLang)) {
+      return locale;
+    }
+  }
+  return DEFAULT_LOCALE;
+}
+
 export function normalizeLocale(locale: string | null | undefined): Locale {
   if (!locale) {
     return DEFAULT_LOCALE;

frontend/src/core/i18n/locales/en-US.ts

@@ -51,6 +51,12 @@ export const enUS: Translations = {
     exportSuccess: "Conversation exported",
   },
 
+  // Home
+  home: {
+    docs: "Docs",
+    blog: "Blog",
+  },
+
   // Welcome
   welcome: {
     greeting: "Hello, again!",

frontend/src/core/i18n/locales/types.ts

@@ -40,6 +40,11 @@ export interface Translations {
     exportSuccess: string;
   };
 
+  home: {
+    docs: string;
+    blog: string;
+  };
+
   // Welcome
   welcome: {
     greeting: string;

frontend/src/core/i18n/locales/zh-CN.ts

@@ -51,6 +51,12 @@ export const zhCN: Translations = {
     exportSuccess: "对话已导出",
   },
 
+  // Home
+  home: {
+    docs: "文档",
+    blog: "博客",
+  },
+
   // Welcome
   welcome: {
     greeting: "你好，欢迎回来！",

frontend/src/core/i18n/server.ts

@@ -1,6 +1,7 @@
 import { cookies } from "next/headers";
 
-import { normalizeLocale, type Locale } from "./locale";
+import { DEFAULT_LOCALE, normalizeLocale, type Locale } from "./locale";
+import { translations } from "./translations";
 
 export async function detectLocaleServer(): Promise<Locale> {
   const cookieStore = await cookies();
@@ -15,3 +16,26 @@ export async function detectLocaleServer(): Promise<Locale> {
 
   return normalizeLocale(locale);
 }
+
+export async function setLocale(locale: string | Locale): Promise<Locale> {
+  const normalizedLocale = normalizeLocale(locale);
+  const cookieStore = await cookies();
+  cookieStore.set("locale", encodeURIComponent(normalizedLocale), {
+    maxAge: 365 * 24 * 60 * 60,
+    path: "/",
+    sameSite: "lax",
+  });
+
+  return normalizedLocale;
+}
+
+export async function getI18n(localeOverride?: string | Locale) {
+  const locale = localeOverride
+    ? normalizeLocale(localeOverride)
+    : await detectLocaleServer();
+  const t = translations[locale] ?? translations[DEFAULT_LOCALE];
+  return {
+    locale,
+    t,
+  };
+}

frontend/src/core/i18n/translations.ts

@@ -0,0 +1,7 @@
+import type { Locale } from "./locale";
+import { enUS, zhCN, type Translations } from "./locales";
+
+export const translations: Record<Locale, Translations> = {
+  "en-US": enUS,
+  "zh-CN": zhCN,
+};