✨ Feature: Add social share images in metadata

[JoshuaKGoldberg]

Bug Report Checklist

• I have searched for related issues and found none that matched my issue.
• This is the appropriate issue form for the bug I would like to report.

Expected

The site should have a social sharing image for links shared on Slack, Twitter, etc.

For now, the square image attached here is fine:

Actual

Screenshot taken in Facebook Messenger:

Screenshot taken in https://cards-dev.twitter.com/validator:

Additional Info

No response