A whole conversation in one call: /getthread

Every conversation on rss.chat has always been walkable through the feeds -- each post's item points at a comments feed, each reply can point at its own, and the threadwalker example assembles a thread that way, one fetch per post, no API needed. Now there's a second door: call /getthread with a post's guid (or id) and the server answers with the post's item record plus a replies array -- each reply the same shape, nested all the way down. You get the post you ask about and everything under it; ask about the root and you get the whole thread. It's one call instead of many, it's less work for the server than serving the walk, and it's the same tree either way. No authentication -- it's an open read, like all the reads. Documented in api.md, with a new example app, getthread, that prints a conversation as an indented outline in one call. (Server v0.6.4, running on rss.chat and demo.rss.chat now.)