Solução do desafio 2

using System.Text.Json.Serialization;

namespace MusicKeyTranslator.Models;

internal class Music
{
    [JsonPropertyName("song")]
    public string? Song { get; set; }
    [JsonPropertyName("key")]
    public int Key { get; set; }
    

    private readonly Dictionary<int, string> dic = new()
    {
        { 0, "C" },
        { 1, "C#" },
        { 2, "D" },
        { 3, "D#" },
        { 4, "E" },
        { 5, "F" },
        { 6, "F#" },
        { 7, "G" },
        { 8, "G#" },
        { 9, "A" },
        { 10, "A#" },
        { 11, "B" },
    };

    public void SearchMusicThroughTone(List<Music> list, string value)
    {
        int position = dic.FirstOrDefault(x => x.Value == value).Key;
        if (position == 1)
        {
            list.RemoveAll(a => a.Key != position);
            foreach (var item in list)
            {
                Console.WriteLine(item.Song + " - " + item.Key);
            }

        }
    }
}

using System.Text.Json;

namespace MusicKeyTranslator.Models;

internal class Service
{
    public static async Task SearchMusic()
    {
        using (HttpClient client = new())
        {
            var response = await client.GetStringAsync("https://guilhermeonrails.github.io/api-csharp-songs/songs.jsonList");
            var jsonList = JsonSerializer.Deserialize<List<Music>>(response)!;
            Music model = new();

            Console.WriteLine("Você quer pegar a tonalidade de qual música?");
            string tom = Console.ReadLine()!;

            model.SearchMusicThroughTone(jsonList, tom);
        }
    }
}