GetBookmarks selected media_file.* without the album cover-stamp projection,
so bookmarked songs kept emitting the pre-edit coverArt id after a cover
upload/delete. With this fourth copy of the projection appearing, extract it
into a shared coverArtUpdatedAtCol helper used by all media_file read paths
(list, playlist tracks, single playlist track, bookmarks).
* Start migration to dbx package
* Fix annotations and bookmarks bindings
* Fix tests
* Fix more tests
* Remove remaining references to beego/orm
* Add PostScanner/PostMapper interfaces
* Fix importing SmartPlaylists
* Renaming
* More renaming
* Fix artist DB mapping
* Fix playlist updates
* Remove bookmarks at the end of the test
* Remove remaining `orm` struct tags
* Fix user timestamps DB access
* Fix smart playlist evaluated_at DB access
* Fix search3
