- POST /api/playlists/{id:int}/items wraps the existing AddItemsToPlaylist
command (mirrors CollectionController.AddItems); controller pre-checks
playlist existence for a real 404, and the handler now rejects adds to
system (generated) playlists, matching the guard already applied to
rename/delete/replace-items so the Blazor path gets the same protection.
- GET /api/search/all-items wraps the existing QuerySearchIndexAllItems
query, returning a new SearchResultAllItemsResponseModel (never expose
the VM directly) so the SPA's shared "add all to collection/playlist"
component can materialize ids before calling the add endpoints, same
two-step flow Blazor's Search.razor already uses.
- Show-detail DTO check: ShowDetailResponseModel already exposes
libraryId, title, and mediaSourceKind (serialized as a string enum via
the global StringEnumConverter) - no changes needed.
Adds controller tests (route table + per-action) for both endpoints and
regenerates the OpenAPI document, endpoint index, and SPA client types.
