refactor: organize services by provider and standardize settings pattern

octo-fiesta/Services/Local/ILocalLibraryService.cs

@@ -0,0 +1,46 @@
+using octo_fiesta.Models;
+
+namespace octo_fiesta.Services.Local;
+
+/// <summary>
+/// Interface for local music library management
+/// </summary>
+public interface ILocalLibraryService
+{
+    /// <summary>
+    /// Checks if an external song already exists locally
+    /// </summary>
+    Task<string?> GetLocalPathForExternalSongAsync(string externalProvider, string externalId);
+    
+    /// <summary>
+    /// Registers a downloaded song in the local library
+    /// </summary>
+    Task RegisterDownloadedSongAsync(Song song, string localPath);
+    
+    /// <summary>
+    /// Gets the mapping between external ID and local ID
+    /// </summary>
+    Task<string?> GetLocalIdForExternalSongAsync(string externalProvider, string externalId);
+    
+    /// <summary>
+    /// Parses a song ID to determine if it is external or local
+    /// </summary>
+    (bool isExternal, string? provider, string? externalId) ParseSongId(string songId);
+    
+    /// <summary>
+    /// Parses an external ID to extract the provider, type and ID
+    /// Format: ext-{provider}-{type}-{id} (e.g., ext-deezer-artist-259, ext-deezer-album-96126, ext-deezer-song-12345)
+    /// Also supports legacy format: ext-{provider}-{id} (assumes song type)
+    /// </summary>
+    (bool isExternal, string? provider, string? type, string? externalId) ParseExternalId(string id);
+    
+    /// <summary>
+    /// Triggers a Subsonic library scan
+    /// </summary>
+    Task<bool> TriggerLibraryScanAsync();
+    
+    /// <summary>
+    /// Gets the current scan status
+    /// </summary>
+    Task<ScanStatus?> GetScanStatusAsync();
+}