fix: remove invalid <config> element in app/page.tsx

Replace incorrect React component with valid one.

#VERCEL_SKIP

Co-authored-by: Anders Lehmann Pier <3219386+AndersPier@users.noreply.github.com>

app/api/health/route.ts

@@ -0,0 +1,12 @@
+import { NextResponse } from "next/server"
+
+export async function GET() {
+  return NextResponse.json(
+    {
+      status: "healthy",
+      timestamp: new Date().toISOString(),
+      service: "markdown-editor",
+    },
+    { status: 200 },
+  )
+}