fix(docs): render raw markdown from page data, not request-time fs read

Every doc page is SSG with revalidate: 1h, so the page component re-runs on
the serverless function whenever it renders outside the prerender cache (ISR
revalidation, cold start, cache miss, RSC payload regeneration). The component
read the raw markdown via fs.readFile(page.data._file.absolutePath) for the
LLMShare copy button, but the content/docs source files are not present in the
function sandbox and the baked-in build-time path does not resolve there, so
the read threw and returned a 500.

This surfaced as intermittent 500s on freshly deployed pages: the build-time
prerendered HTML is cached at the edge (200), but the first origin hit at a
cold POP — e.g. LinkedIn's crawler scraping a new changelog URL — got the 500
error page and cached it as the link preview.

Use page.data.content (the raw markdown fumadocs bundles into the function),
matching how lib/get-llm-text.ts already sources content for the /llms.mdx
route. No filesystem access at request time, no 500.

Author: nibzard

app/[...slug]/page.tsx

@@ -1,5 +1,4 @@
 //@ts-nocheck
-import fs from 'node:fs/promises';
 import defaultMdxComponents from 'fumadocs-ui/mdx';
 import matter from 'gray-matter';
 import * as lucideIcons from 'lucide-react';
@@ -44,8 +43,11 @@ export default async function Page(props: {
   }
 
   if (!page) notFound();
-  const fileContent = await fs.readFile(page.data._file.absolutePath, 'utf-8');
-  const { content: rawMarkdownContent } = matter(fileContent);
+  // Use the raw markdown bundled into page.data.content rather than reading the
+  // source file from disk at request time. The content/docs source files are not
+  // present in the serverless function sandbox, so a filesystem read throws and
+  // returns a 500 whenever the page renders outside the prerender cache.
+  const { content: rawMarkdownContent } = matter(page.data.content);
 
   const LLMContent = rawMarkdownContent
     .split('\n')