Request

Add HEY World commands so posts can be managed without the app, for example:

hey world list                 # list my published posts (id, title, url, date)
hey world show <post>          # view one post
hey world publish --subject "Title" < post.md   # publish, returning the post URL
hey world edit <post> ...      # update title/body
hey world unpublish <post>     # take a post down / delete it

Why

Publishing today means hey compose --to world@hey.com. There's no way to list, fix, or remove a post from the CLI. When something goes wrong, like the duplicate posts in #556, cleanup has to happen in the app. Scripts and agents that publish need a matching way to verify and undo.

Notes

• publish should return the post's URL and id, so callers can check it was published instead of retrying.
• unpublish should be clear about whether it deletes the post or just hides it, and whether subscribers already got it by email.
• list --json would let tools check for duplicates before publishing.

Related: #556.

hey version 1.8.0