A repository's activity.atom and waves.atom parse as Atom: each has a feed id, updated, self link and entries with id, title, updated and link

Feed readers are a door to the story. Today nothing checks that the feeds (src/web/feeds.ts, src/web/pages/waves.ts) stay well formed.

Done when:

[ ] A test fetches /:owner/:name/activity.atom and /:owner/:name/waves.atom for a seeded repository, parses each as XML, and checks the Atom shape. That means a feed id, title, updated, a link rel=self that equals its own URL, and every entry with id, title, updated (RFC 3339) and link.
[ ] An entry whose title has &, < and an emoji parses, and reads back unchanged.
[ ] Both answer application/atom+xml with their ETag. A repeat with If-None-Match is a 304.
[ ] Any feed found malformed is fixed in the same pull.

A repository's activity.atom and waves.atom parse as Atom: each has a feed id, updated, self link and entries with id, title, updated and link #5958