Build a Job Board component in React that displays the latest job postings from Hacker News.

Requirements:

1. Display a list of job postings with the following details:
   • Job title
   • Company name
   • Poster username
   • Time posted
   • Link to the job posting (if available)
2. Fetch job postings from the Hacker News API.
3. Show 6 job postings initially, with a button to load more.
4. Clicking on the job title should open the job posting in a new tab (if a URL is provided).
5. Focus on functionality over styling.
6. The component should work out-of-the-box in a live React preview (e.g., CodeSandbox/Sandpack).