Likes returned `url`, which is the liked post rather than our page. Use
`uri` instead. Bookmarks already asked for `uri`, which didn't exist until
the previous commit, so their Location header was empty.
Neither case had a test, so assert the header value for both.
Refs #148
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Jonny Barnes
e8f2535cd1