feat: add subsonic proxy architecture with external music services

- Add MusicModels (Song, Artist, Album, SearchResult, DownloadInfo)
- Add IMusicMetadataService and DeezerMetadataService for external search
- Add IDownloadService and DeezspotDownloadService for downloads
- Add LocalLibraryService for managing downloaded songs cache
- Add custom endpoints: search3, stream, getSong, getAlbum, getCoverArt
- Configure dependency injection for all services

octo-fiesta/Models/MusicModels.cs

@@ -0,0 +1,114 @@
+namespace octo_fiesta.Models;
+
+/// <summary>
+/// Représente une chanson (locale ou externe)
+/// </summary>
+public class Song
+{
+    /// <summary>
+    /// ID unique. Pour les chansons externes, préfixé avec "ext-" + provider + "-" + id externe
+    /// Exemple: "ext-deezer-123456" ou "local-789"
+    /// </summary>
+    public string Id { get; set; } = string.Empty;
+    
+    public string Title { get; set; } = string.Empty;
+    public string Artist { get; set; } = string.Empty;
+    public string? ArtistId { get; set; }
+    public string Album { get; set; } = string.Empty;
+    public string? AlbumId { get; set; }
+    public int? Duration { get; set; } // En secondes
+    public int? Track { get; set; }
+    public int? Year { get; set; }
+    public string? Genre { get; set; }
+    public string? CoverArtUrl { get; set; }
+    
+    /// <summary>
+    /// Indique si la chanson est disponible localement ou doit être téléchargée
+    /// </summary>
+    public bool IsLocal { get; set; }
+    
+    /// <summary>
+    /// Provider externe (deezer, spotify, etc.) - null si local
+    /// </summary>
+    public string? ExternalProvider { get; set; }
+    
+    /// <summary>
+    /// ID sur le provider externe (pour le téléchargement)
+    /// </summary>
+    public string? ExternalId { get; set; }
+    
+    /// <summary>
+    /// Chemin du fichier local (si disponible)
+    /// </summary>
+    public string? LocalPath { get; set; }
+}
+
+/// <summary>
+/// Représente un artiste
+/// </summary>
+public class Artist
+{
+    public string Id { get; set; } = string.Empty;
+    public string Name { get; set; } = string.Empty;
+    public string? ImageUrl { get; set; }
+    public int? AlbumCount { get; set; }
+    public bool IsLocal { get; set; }
+    public string? ExternalProvider { get; set; }
+    public string? ExternalId { get; set; }
+}
+
+/// <summary>
+/// Représente un album
+/// </summary>
+public class Album
+{
+    public string Id { get; set; } = string.Empty;
+    public string Title { get; set; } = string.Empty;
+    public string Artist { get; set; } = string.Empty;
+    public string? ArtistId { get; set; }
+    public int? Year { get; set; }
+    public int? SongCount { get; set; }
+    public string? CoverArtUrl { get; set; }
+    public string? Genre { get; set; }
+    public bool IsLocal { get; set; }
+    public string? ExternalProvider { get; set; }
+    public string? ExternalId { get; set; }
+    public List<Song> Songs { get; set; } = new();
+}
+
+/// <summary>
+/// Résultat de recherche combinant résultats locaux et externes
+/// </summary>
+public class SearchResult
+{
+    public List<Song> Songs { get; set; } = new();
+    public List<Album> Albums { get; set; } = new();
+    public List<Artist> Artists { get; set; } = new();
+}
+
+/// <summary>
+/// État du téléchargement d'une chanson
+/// </summary>
+public enum DownloadStatus
+{
+    NotStarted,
+    InProgress,
+    Completed,
+    Failed
+}
+
+/// <summary>
+/// Information sur un téléchargement en cours ou terminé
+/// </summary>
+public class DownloadInfo
+{
+    public string SongId { get; set; } = string.Empty;
+    public string ExternalId { get; set; } = string.Empty;
+    public string ExternalProvider { get; set; } = string.Empty;
+    public DownloadStatus Status { get; set; }
+    public double Progress { get; set; } // 0.0 à 1.0
+    public string? LocalPath { get; set; }
+    public string? ErrorMessage { get; set; }
+    public DateTime StartedAt { get; set; }
+    public DateTime? CompletedAt { get; set; }
+}