fix: resolve two remaining Vercel build failures

1. app/layout.tsx: strip surrounding quotes from NEXT_PUBLIC_SITE_URL
   Environment variable was configured with extra double-quotes
   (e.g. '"https://involutionhell.com"'), causing new URL() to throw
   ERR_INVALID_URL at page-data collection time.

2. lib/source.ts: eagerly resolve fumadocs-mdx lazy files function
   fumadocs-mdx@11.x returns `files` as a lazy function in
   toFumadocsSource(), but fumadocs-core@15.8.x buildContentStorage
   calls files.map() directly expecting an array. Mutate the source
   object before passing to loader() to bridge the incompatibility.

https://claude.ai/code/session_01YGNupgHxmKvUdpX1x72xjR

Author: claude

app/layout.tsx

@@ -23,8 +23,9 @@ const geistMono = localFont({
   weight: "100 900",
 });
 
-const SITE_URL =
-  process.env.NEXT_PUBLIC_SITE_URL || "https://involutionhell.com";
+const SITE_URL = (
+  process.env.NEXT_PUBLIC_SITE_URL || "https://involutionhell.com"
+).replace(/^["']|["']$/g, "");
 const en_description =
   "内卷地狱（Involution Hell）是一个由开发者发起的开源学习社区，专注算法、系统设计、工程实践与技术分享，帮助华人程序员高效成长，专注真实进步。Involution Hell is an open-source community empowering builders with real-world engineering.";
 

lib/source.ts

@@ -19,9 +19,19 @@ function convertSlugToPinyin(text: string) {
     .join("-");
 }
 
+// fumadocs-mdx@11.x returns `files` as a lazy function,
+// but fumadocs-core@15.8.x buildContentStorage calls files.map() directly.
+// Eagerly resolve the files array to maintain compatibility.
+const _fumaSource = docs.toFumadocsSource();
+if (typeof _fumaSource.files === "function") {
+  (_fumaSource as { files: unknown }).files = (
+    _fumaSource.files as () => unknown[]
+  )();
+}
+
 export const source = loader({
   baseUrl: "/docs",
-  source: docs.toFumadocsSource(),
+  source: _fumaSource,
   transformers: [
     ({ storage }) => {
       for (const path of storage.getFiles()) {