Refactor navigation links to use Next.js routing and improve post handling

- Updated AboutButton to navigate to the about page using Next.js router.
- Changed HeaderButtons and MobileNav to link directly to the about page.
- Modified Home component to exclude the 'about' post from the posts list.
- Added a helper function to strip YAML frontmatter from post summaries.
- Enhanced API routes to handle reading and writing markdown files for posts.

src/app/api/posts/[slug]/route.ts

@@ -19,6 +19,13 @@ export async function GET(
     );
     if (rustResult.status === 0 && rustResult.stdout) {
       const post = JSON.parse(rustResult.stdout);
+      const fs = require('fs');
+      const filePath = path.join(postsDirectory, slugPath + '.md');
+      let raw = '';
+      try {
+        raw = fs.readFileSync(filePath, 'utf8');
+      } catch {}
+      post.raw = raw;
       post.createdAt = post.created_at;
       delete post.created_at;
       return NextResponse.json(post);
@@ -33,4 +40,20 @@ export async function GET(
     );
   }
 }
+
+export async function POST(request: Request, { params }: { params: { slug: string[] | string } }) {
+  try {
+    const { markdown } = await request.json();
+    if (typeof markdown !== 'string') {
+      return NextResponse.json({ error: 'Invalid markdown' }, { status: 400 });
+    }
+    const slugArr = Array.isArray(params.slug) ? params.slug : [params.slug];
+    const slugPath = slugArr.join('/');
+    const filePath = path.join(postsDirectory, slugPath + '.md');
+    require('fs').writeFileSync(filePath, markdown, 'utf8');
+    return NextResponse.json({ success: true });
+  } catch (error) {
+    return NextResponse.json({ error: 'Error saving file', details: error instanceof Error ? error.message : 'Unknown error' }, { status: 500 });
+  }
+}