wip: partial implementation salvaged from interrupted workflow run

Untrusted draft — no build/test had run yet. Review before building on it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ErsatzTV/Controllers/Api/FillerPresetController.cs

@@ -0,0 +1,19 @@
+using ErsatzTV.Application.Filler;
+using ErsatzTV.Core.Api.Filler;
+using MediatR;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+
+namespace ErsatzTV.Controllers.Api;
+
+[ApiController]
+public class FillerPresetController(IMediator mediator) : ControllerBase
+{
+    [HttpGet("/api/filler-presets")]
+    [Tags("Filler Presets")]
+    [EndpointSummary("Get all filler presets")]
+    [EndpointGroupName("general")]
+    [ProducesResponseType(typeof(List<FillerPresetResponseModel>), StatusCodes.Status200OK)]
+    public async Task<List<FillerPresetResponseModel>> GetAll(CancellationToken cancellationToken) =>
+        await mediator.Send(new GetAllFillerPresetsForApi(), cancellationToken);
+}