feat(api): playlist add-items + search all-items endpoints (#208 #209)

- 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.

ErsatzTV/Controllers/Api/PlaylistController.cs

@@ -222,6 +222,31 @@ public class PlaylistController(IMediator mediator) : ControllerBase
             None: () => new NoContentResult());
     }
 
+    [HttpPost("/api/playlists/{id:int}/items", Name = "AddItemsToPlaylist")]
+    [Tags("Playlists")]
+    [EndpointSummary("Add items to a playlist")]
+    [EndpointGroupName("general")]
+    [ProducesResponseType(StatusCodes.Status204NoContent)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status422UnprocessableEntity)]
+    public async Task<IActionResult> AddItems(
+        int id,
+        [Required] [FromBody] AddItemsToPlaylistRequest request,
+        CancellationToken cancellationToken)
+    {
+        Option<PlaylistViewModel> maybePlaylist = await mediator.Send(new GetPlaylistById(id), cancellationToken);
+        if (maybePlaylist.IsNone)
+        {
+            return ApiResults.NotFoundProblem();
+        }
+
+        // System (generated) playlists must not have items added. The AddItemsToPlaylistHandler
+        // also enforces this (defense-in-depth for the Blazor path, which calls the same command
+        // from MultiSelectBase.AddItemsToPlaylist).
+        Either<BaseError, Unit> result = await mediator.Send(request.ToCommand(id), cancellationToken);
+        return result.ToDeletedResult();
+    }
+
     [HttpPost("/api/playlists/preview", Name = "PreviewPlaylist")]
     [Tags("Playlists")]
     [EndpointSummary("Preview the playout of a draft playlist")]

ErsatzTV/Controllers/Api/Requests/AddItemsToPlaylistRequest.cs

@@ -0,0 +1,30 @@
+using ErsatzTV.Application.MediaCollections;
+
+namespace ErsatzTV.Controllers.Api.Requests;
+
+public record AddItemsToPlaylistRequest(
+    List<int> MovieIds,
+    List<int> ShowIds,
+    List<int> SeasonIds,
+    List<int> EpisodeIds,
+    List<int> ArtistIds,
+    List<int> MusicVideoIds,
+    List<int> OtherVideoIds,
+    List<int> SongIds,
+    List<int> ImageIds,
+    List<int> RemoteStreamIds)
+{
+    public AddItemsToPlaylist ToCommand(int playlistId) =>
+        new(
+            playlistId,
+            MovieIds ?? [],
+            ShowIds ?? [],
+            SeasonIds ?? [],
+            EpisodeIds ?? [],
+            ArtistIds ?? [],
+            MusicVideoIds ?? [],
+            OtherVideoIds ?? [],
+            SongIds ?? [],
+            ImageIds ?? [],
+            RemoteStreamIds ?? []);
+}

ErsatzTV/Controllers/Api/SearchController.cs

@@ -39,6 +39,30 @@ public class SearchController(IMediator mediator) : ControllerBase
         return new OkObjectResult(result);
     }
 
+    [HttpGet("/api/search/all-items", Name = "SearchAllItems")]
+    [Tags("Search")]
+    [EndpointSummary("Search library items across all media kinds and return raw id lists")]
+    [EndpointDescription(
+        "Returns every matching item's id, grouped by media kind, with no paging. Used by the SPA's " +
+        "\"add all to collection/playlist\" flow to materialize ids before calling the add endpoints.")]
+    [EndpointGroupName("general")]
+    [ProducesResponseType(typeof(SearchResultAllItemsResponseModel), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status422UnprocessableEntity)]
+    public async Task<IActionResult> SearchAllItems(
+        [FromQuery] string query = "",
+        CancellationToken cancellationToken = default)
+    {
+        if (string.IsNullOrWhiteSpace(query))
+        {
+            return BaseError.New("A non-empty query is required").ToErrorResult();
+        }
+
+        SearchResultAllItemsViewModel result = await mediator.Send(
+            new QuerySearchIndexAllItems(query),
+            cancellationToken);
+        return new OkObjectResult(Project(result));
+    }
+
     [HttpGet("/api/search/collections", Name = "SearchCollections")]
     [Tags("Search")]
     [EndpointSummary("Search collections by name")]
@@ -134,4 +158,17 @@ public class SearchController(IMediator mediator) : ControllerBase
             cancellationToken);
         return results.Map(c => new SchedulingPickerOptionResponseModel(c.Id, c.Name)).ToList();
     }
+
+    private static SearchResultAllItemsResponseModel Project(SearchResultAllItemsViewModel vm) =>
+        new(
+            vm.MovieIds,
+            vm.ShowIds,
+            vm.SeasonIds,
+            vm.EpisodeIds,
+            vm.ArtistIds,
+            vm.MusicVideoIds,
+            vm.OtherVideoIds,
+            vm.SongIds,
+            vm.ImageIds,
+            vm.RemoteStreamIds);
 }