feat: serve content files via catch-all route, use content-relative cover images

app/content/[...path]/route.ts

@@ -0,0 +1,42 @@
+import { NextResponse } from 'next/server';
+import { readFileSync, existsSync } from 'node:fs';
+import { join } from 'node:path';
+
+const CONTENT_DIR = join(process.cwd(), 'content');
+
+const MIME_TYPES: Record<string, string> = {
+  '.jpg': 'image/jpeg',
+  '.jpeg': 'image/jpeg',
+  '.png': 'image/png',
+  '.gif': 'image/gif',
+  '.webp': 'image/webp',
+  '.svg': 'image/svg+xml',
+  '.pdf': 'application/pdf',
+  '.txt': 'text/plain',
+  '.md': 'text/plain',
+  '.mdx': 'text/plain',
+};
+
+export async function GET(
+  _request: Request,
+  { params }: { params: Promise<{ path: string[] }> },
+) {
+  const { path } = await params;
+  const decodedPath = decodeURIComponent(path.join('/'));
+  const fullPath = join(CONTENT_DIR, decodedPath);
+
+  if (!fullPath.startsWith(CONTENT_DIR) || !existsSync(fullPath)) {
+    return new NextResponse('Not found', { status: 404 });
+  }
+
+  const ext = '.' + fullPath.split('.').pop()!;
+  const contentType = MIME_TYPES[ext] ?? 'application/octet-stream';
+  const data = readFileSync(fullPath);
+
+  return new NextResponse(data, {
+    headers: {
+      'Content-Type': contentType,
+      'Cache-Control': 'public, max-age=31536000, immutable',
+    },
+  });
+}

content/posts/euler-identity.mdx

@@ -7,7 +7,7 @@ tags:
   - mathematics
   - euler
   - complex-numbers
-coverImage: /images/euler-cover.jpg
+coverImage: /content/posts/euler-identity/euler-cover.jpg
 ---
 
 Euler's identity is widely regarded as the most beautiful equation in all of mathematics:

content/posts/hello-world.mdx

@@ -7,7 +7,7 @@ tags:
   - typescript
   - programming
   - tutorial
-coverImage: /images/typescript-cover.jpg
+coverImage: /content/posts/hello-world/typescript-cover.jpg
 ---
 
 Welcome to this comprehensive TypeScript tutorial! Whether you are migrating a JavaScript project or starting fresh, this guide will walk you through TypeScript's type system from fundamentals to advanced patterns used in production codebases.

content/posts/hybrid-post.mdx

@@ -8,7 +8,7 @@ tags:
   - signal-processing
   - tutorial
 author: James Liu
-coverImage: /images/fourier-cover.jpg
+coverImage: /content/posts/hybrid-post/fourier-cover.jpg
 ---
 
 ## Fourier Analysis: From Mathematical Theory to Python Practice

next.config.ts

@@ -1,9 +1,7 @@
 import type { NextConfig } from 'next'
 
 const nextConfig: NextConfig = {
-  // Static export — generates out/ directory with plain HTML
+  // Trailing slash for clean URLs
-  output: 'export',
-  // Trailing slash for clean static URLs
   trailingSlash: true,
   // Images: unoptimized required for static export
   images: {