feat: add database connections, initial migration and early CLI tooling

Entities/Song.cs

@@ -0,0 +1,59 @@
+using System.Numerics;
+
+namespace Shadow.Entities;
+public class Song
+{
+	public int Id { get; set; }
+	required public string Title { get; set; }
+	required public string Uri { get; set; }
+	required public string Filepath { get; set; }
+	public int State { get; set; }
+	required public string Filetype { get; set; }
+	public DateTime Date { get; set; }
+	public int Duration { get; set; }
+	public int Bitrate { get; set; }
+	public int Size { get; set; }
+	public string? Comment { get; set; } = null;
+	public int Channels { get; set; } = 2;
+	public int SamplingRate { get; set; }
+	public int? BitDepth { get; set; } = null;
+	public int Index { get; set; }
+	public int? TrackNumber { get; set; } = null;
+	public int? DiscNumber { get; set; } = null;
+	required public int AlbumId { get; set; }
+	required public int ArtistId { get; set; }
+	public int? ImageId { get; set; } = null;
+
+	// Songs without an album entry shall default to "[Unnamed album]".
+	required public Album Album { get; set; }
+	// Same for artists, with "[Unknown artist]".
+	required public Artist Artist { get; set; }
+	public List<GenreSong> GenreSongPair { get; set; } = [];
+	public Image? Image { get; set; } = null;
+
+	public bool IsOk() => State == 0;
+	public bool IsOrphaned() => State == 1;
+	public bool IsArchived() => State == 2;
+	public string GetMimeType()
+	{
+		// Might be nice to rewrite like this later:
+		// https://stackoverflow.com/a/47601452
+		string mimeType = String.Empty;
+		switch (Filetype)
+		{
+			case "flac":
+				mimeType =    "audio/flac"; break;
+			case "m4a":
+				mimeType =     "audio/mp4"; break;
+			case "mp3":
+				mimeType =    "audio/mpeg"; break;
+			case "ogg":
+				mimeType =     "audio/ogg"; break;
+			case "wav":
+				mimeType =   "audio/x-wav"; break;
+			default:
+				mimeType = "audio/unknown"; break;
+		}
+		return mimeType;
+	}
+}