Create withHarper() Next.js config utility #805

Request

Provide a withHarper(nextConfig) utility that wraps the user's Next.js config and applies all necessary adjustments to make Harper work correctly (e.g., webpack externals, server external packages). Reduces boilerplate and keeps integration details out of user code.

// next.config.js
const { withHarper } = require('harperdb/next');
module.exports = withHarper({ /* next config */ });

Related: CORE-2601 (serverExternalPackages investigation)

🤖 Filed by Claude on behalf of Kris.