A to-do list for the site itself.

Add digital garden items to posts.json

Which is what powers search. Also, search needs to be able to show what's a post and what's a garden item.

Put the backlinks in a nicer spot

The sidebar? Left or right? Look at how other do backlinks.

A nicer garden 404 page (for stubs and the like)

Not just a generic 404...

A table of contents?

Or, how do I arrange garden items so they don't get completely lost?