feat(growth): UTM 跟踪 doc 分享链接 + turbopack root 锁定

恢复自 i18n PR 之前 stash 出来的 utm-tracking 工作。

UTM 跟踪：
- README badge / logo 链接加 utm_source=github,utm_medium=readme,
  utm_campaign={logo,badge}，让 GA Source 维度看到 GitHub 入站流量
- DocShareButton 复制链接时打 utm_source=doc_share,utm_medium=user_share，
  用户分享到 DC/微信/X 后回流在 GA 看到，区别于 (direct)/(none)

turbopack root：
- next.config.mjs 显式锁定 turbopack root 和 outputFileTracingRoot 到
  frontend/ 自己目录。Next.js 16 默认会向上搜 lockfile 推 workspace root，
  开发机上 /home/ubuntu/package-lock.json 之类的会把 root 推到上层，
  turbopack 解析 node_modules 错位 → "Can't resolve 'tailwindcss'" 类报错。

Author: github-actions[bot]

README.en.md

@@ -3,7 +3,7 @@
 </p>
 
 <p align="center">
-  <a href="https://involutionhell.com">
+  <a href="https://involutionhell.com/?utm_source=github&utm_medium=readme&utm_campaign=logo">
     <picture>
       <!-- Dark mode logo -->
       <source media="(prefers-color-scheme: dark)" srcset="./public/logo/logoInDark.svg">
@@ -21,7 +21,7 @@
   <img alt="Next.js" src="https://img.shields.io/badge/Next.js-000000?style=for-the-badge&logo=nextdotjs&logoColor=white" />
   <img alt="Vercel" src="https://img.shields.io/badge/Vercel-000000?style=for-the-badge&logo=vercel&logoColor=white" />
   <a href="https://github.com/InvolutionHell/involutionhell/blob/main/LICENSE">
-  <a href="https://involutionhell.com">
+  <a href="https://involutionhell.com/?utm_source=github&utm_medium=readme&utm_campaign=badge">
     <img src="https://img.shields.io/badge/Website-involutionhell.com-blue?style=for-the-badge" alt="Official Website">
   </a>
 </p>

README.md

@@ -3,7 +3,7 @@
 </p>
 
 <p align="center">
-  <a href="https://involutionhell.com">
+  <a href="https://involutionhell.com/?utm_source=github&utm_medium=readme&utm_campaign=logo">
     <picture>
       <!-- Dark mode logo -->
       <source media="(prefers-color-scheme: dark)" srcset="./public/logo/logoInDark.svg">
@@ -21,7 +21,7 @@
   <img alt="Next.js" src="https://img.shields.io/badge/Next.js-000000?style=for-the-badge&logo=nextdotjs&logoColor=white" />
   <img alt="Vercel" src="https://img.shields.io/badge/Vercel-000000?style=for-the-badge&logo=vercel&logoColor=white" />
   <a href="https://github.com/InvolutionHell/involutionhell/blob/main/LICENSE">
-  <a href="https://involutionhell.com">
+  <a href="https://involutionhell.com/?utm_source=github&utm_medium=readme&utm_campaign=badge">
     <img src="https://img.shields.io/badge/Website-involutionhell.com-blue?style=for-the-badge" alt="Official Website">
   </a>
 </p>

app/components/DocShareButton.tsx

@@ -20,7 +20,12 @@ export function DocShareButton() {
   }, []);
 
   const handleCopy = async () => {
-    const url = window.location.href;
+    // 用户点"复制链接"必然是要发到外面（DC/微信/X）
+    // 给链接打上 UTM，回流时能在 GA Source 维度看到 doc_share，区别于 (direct)
+    const target = new URL(window.location.href);
+    target.searchParams.set("utm_source", "doc_share");
+    target.searchParams.set("utm_medium", "user_share");
+    const url = target.toString();
     try {
       await navigator.clipboard.writeText(url);
       setCopied(true);

next.config.mjs

@@ -1,8 +1,18 @@
 // next.config.mjs
+import path from "node:path";
+import { fileURLToPath } from "node:url";
 import { createMDX } from "fumadocs-mdx/next";
 import createNextIntlPlugin from "next-intl/plugin";
 import { withSentryConfig } from "@sentry/nextjs";
 
+// Next.js 16 detects multi-lockfile environments by searching upward for
+// pnpm-lock.yaml / package-lock.json / yarn.lock. 当父目录意外有 lockfile
+// 时（如开发服务器上 /home/ubuntu/package-lock.json），Next 会把 workspace
+// root 推到上层，turbopack 跟着到错的目录解析 node_modules，
+// 触发 "Can't resolve 'tailwindcss'" 之类报错。
+// 显式锁定到 frontend 自己目录，turbopack + outputFileTracing 双保险。
+const projectRoot = path.dirname(fileURLToPath(import.meta.url));
+
 /**
  * IMPORTANT: remarkImage 配置已移至 source.config.ts 统一管理
  *
@@ -22,6 +32,12 @@ const withNextIntl = createNextIntlPlugin("./i18n/request.ts");
 /** @type {import('next').NextConfig} */
 const config = {
   reactStrictMode: true,
+  // 强制锁定 turbopack 和 SSR file tracing 的根目录到 frontend/ 自己，
+  // 避免上层意外 lockfile 把 root 推错（详见文件顶部注释）。
+  turbopack: {
+    root: projectRoot,
+  },
+  outputFileTracingRoot: projectRoot,
   /**
    * docs 目录整理产生的 URL 变化 → 301 重定向。
    *