Per-page OG images on an Astro site, without the SaaS

Every page on dacforge.com now has its own Open Graph image. The services hub has one image. Each of the ten service pages has its own. Each blog post has its own. The about page, the privacy page, and every other public URL on the site has a distinct card that shows up when someone pastes the link into LinkedIn, X, Mastodon, or Slack. There is no Cloudinary account. No Vercel OG. No external image service. The whole thing runs at astro build , writes PNGs into dist/og/ , and that is the last an