Create a new `link` post type for commenting on other sites

[cuibonobo]

Though maybe it should be called bookmark as suggested by this Indie Web post? From looking at a few examples, these posts should display:

• The full title of the page, which links directly to the page
• The domain of the page
• The date retrieved
• Highlights in a distinctive style that communicate that they are from the linked page
• My own commentary on the link
• An optional archive link

These posts could also have tags like metadata:unread in order to keep track of links I want to read later.

Posts could be generated manually at first, but ideally these would be created by a browser extension on Desktop browsers or via the share sheet on mobile.

[cuibonobo]

I'd like for these posts to show up in the 'Ephemera' section of the site, so the ephemera post type should change to a (more standard) note type.

[cuibonobo]

Showing multiple post types in the same feed is referenced in #68.

[cuibonobo]

Exploring this idea further, maybe reference is the most generic case?