实现GetFiles和GenerateFfMpegCommand，批量创建命令。

using System.ComponentModel;

using shRabbit.Base.IO.Directories;

using shRabbit.Base.IO.Files;

using Spectre.Console;

using Spectre.Console.Cli;

namespace VideoSlice.Cli;

        [CommandOption("-d|--dir")]

        [Description("选择的视频目录。")]

        public string? Directory { get; set; }

        public string Directory { get; set; } = string.Empty;

        [CommandOption("-f|--ffmpeg")]

        [CommandOption("-s|--desc")]

        [Description("图像文件输出目录。")]

        public string Desc { get; set; } = "output";

        [CommandOption("-fm|--format")]

        [Description("图像格式（默认png）。")]

        public string Format { get; set; } = "png";

        [CommandOption("-fm|--format")]

        [Description("视频格式（默认mp4，可用','使用多个）。")]

        public string VideoFormats { get; set; } = "mp4";

        [CommandOption("-p|-parallel")]

        [Description("并行处理数量。")]

        public uint ParallelNumber { get; set; } = 4;

        [CommandOption("-m|--ffmpeg")]

        [Description("FFmpeg命令行程序的路径。")]

        public string FfMpegPath { get; set; } = "ffmpeg";

        [CommandOption("-s|--slice")]

        [Description("将视频按照时长切分的间隔时间（默认30m）。")]

        public string SliceTime { get; set; } = "30m";

    }

    /// <summary>

    /// 生成 ffmpeg 调用参数。

    /// </summary>

    /// <param name="settings"></param>

    /// <param name="file"></param>

    /// <param name="dir"></param>

    /// <returns>两层数组，第一次是每个命令，第二次是命令中的参数。</returns>

    public static string[][] GenerateFfMpegCommand(Settings settings, IFile file, IDirectory dir)

    {

        var files = GetFiles(settings, dir);

        var arr = new string[files.Length][];

        var time = SimpleTimeSpanExpress.ToTimeSpan(settings.SliceTime);

        for (var i = 0; i < arr.Length; i++)

        {

            arr[i] = ["-i", files[i], "-vf", $"\"fps:1/{time.TotalSeconds}\"", $"{settings.Desc}{files[i]}_%03d.{settings.Format}"];

        }

        return arr;

    }

    public static string[] GetFiles(Settings settings, IDirectory dir)

    {

        if (settings.File is { } s) return [s];

        var split = settings.VideoFormats.Split(',');

        var list = new List<string>();

        foreach (var f in dir.EnumerateFiles(settings.Directory))

        {

            foreach (var sp in split)

            {

                if (Path.GetExtension(f).TrimStart('.') == sp.TrimStart('.'))

                {

                    AnsiConsole.WriteLine($"找到: {f}");

                    list.Add(f);

                }

            }

        }

        return list.ToArray();

    }

    protected override async Task<int> ExecuteAsync(CommandContext context, Settings settings, CancellationToken cancellationToken)