Design spec and bite-sized TDD implementation plan for #489, whose
implementation landed in #493.
Docs-only. Kept as the record of how the design was reached: that Jellyfin
classifies mixed-library items server-side via includeItemTypes (so no
inference is needed), that MediaItem is TPT keyed on LibraryPathId (so no
migration is needed), that MediaKind is dispatch + presentation only, and why
the feature is deliberately scoped to Jellyfin rather than local libraries.
Also records the open risk the plan carried -- the music-video scanner's
untraced reconciliation -- which #494 subsequently answered.
Refs #489
Co-authored-by: Timothy <timothy.look@gmail.com>
Co-committed-by: Timothy <timothy.look@gmail.com>
