Iris will continue to use kind 1 instead of kind 20 for image post creation:

* Works on most clients, doesn't break existing clients' reaction / reply based feeds

* Kind 1 events reach larger audience than 20

* No added complexity, no different handling for kind 20. Keep nostr client implementation simple.

* Clients that don't support images can just show the text content, or filter out notes that have images

* Clients that only want images can filter out posts that don't have images

* Optionally, they can use ['l', 'picture-first'] or similar tag for relay indexing of image posts