Add shared pagination, projections and ownership helpers; simplify query and command handlers

backend/Core/Musify.Application/Genres/GetAvailableGenres.cs

@@ -1,12 +1,11 @@
 using Mediator;
 using Musify.Domain.ValueObjects;
+using Musify.Application.Genres.Responses;
 
 namespace Musify.Application.Genres;
 
 public record GetAvailableGenresQuery : IQuery<IReadOnlyList<AvailableGenreResponse>>;
 
-public record AvailableGenreResponse(Genre Genre, IReadOnlyList<Genre> IncompatibleWith);
-
 public class GetAvailableGenresQueryHandler
     : IQueryHandler<GetAvailableGenresQuery, IReadOnlyList<AvailableGenreResponse>>
 {

backend/Core/Musify.Application/Genres/GetGenres.cs

@@ -2,13 +2,12 @@ using Mediator;
 using Microsoft.EntityFrameworkCore;
 using Musify.Application.Contracts;
 using Musify.Domain.ValueObjects;
+using Musify.Application.Genres.Responses;
 
 namespace Musify.Application.Genres;
 
 public record GetGenresQuery : IQuery<IReadOnlyList<GenreResponse>>;
 
-public record GenreResponse(Genre Genre, int TrackCount);
-
 public class GetGenresQueryHandler(IDatabase database)
     : IQueryHandler<GetGenresQuery, IReadOnlyList<GenreResponse>>
 {

backend/Core/Musify.Application/Genres/Responses/AvailableGenreResponse.cs

@@ -0,0 +1,5 @@
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Genres.Responses;
+
+public record AvailableGenreResponse(Genre Genre, IReadOnlyList<Genre> IncompatibleWith);

backend/Core/Musify.Application/Genres/Responses/GenreResponse.cs

@@ -0,0 +1,5 @@
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Genres.Responses;
+
+public record GenreResponse(Genre Genre, int TrackCount);