v1.2.1: MusicBrainz genre enrichment + cleanup

## Features
- Implement automatic MusicBrainz genre enrichment for all external sources
  - Deezer: Enriches when genre missing
  - Qobuz: Enriches when genre missing
  - SquidWTF/Tidal: Always enriches (Tidal doesn't provide genres)
- Use ISRC codes for exact matching, fallback to title/artist search
- Cache results in Redis (30 days) + file cache for performance
- Respect MusicBrainz rate limits (1 req/sec)

## Cleanup
- Remove unused Spotify API ClientId and ClientSecret settings
- Simplify Spotify API configuration

## Fixes
- Make GenreEnrichmentService optional to fix test failures
- All 225 tests passing

This ensures all external tracks have genre metadata for better
organization and filtering in music clients.

allstarr/Services/Deezer/DeezerMetadataService.cs

@@ -16,13 +16,13 @@ public class DeezerMetadataService : IMusicMetadataService
 {
     private readonly HttpClient _httpClient;
     private readonly SubsonicSettings _settings;
-    private readonly GenreEnrichmentService _genreEnrichment;
+    private readonly GenreEnrichmentService? _genreEnrichment;
     private const string BaseUrl = "https://api.deezer.com";
 
     public DeezerMetadataService(
         IHttpClientFactory httpClientFactory, 
         IOptions<SubsonicSettings> settings,
-        GenreEnrichmentService genreEnrichment)
+        GenreEnrichmentService? genreEnrichment = null)
     {
         _httpClient = httpClientFactory.CreateClient();
         _settings = settings.Value;
@@ -210,7 +210,7 @@ public class DeezerMetadataService : IMusicMetadataService
         }
         
         // Enrich with MusicBrainz genres if missing
-        if (string.IsNullOrEmpty(song.Genre))
+        if (_genreEnrichment != null && string.IsNullOrEmpty(song.Genre))
         {
             await _genreEnrichment.EnrichSongGenreAsync(song);
         }

allstarr/Services/Qobuz/QobuzMetadataService.cs

@@ -19,7 +19,7 @@ public class QobuzMetadataService : IMusicMetadataService
     private readonly SubsonicSettings _settings;
     private readonly QobuzBundleService _bundleService;
     private readonly ILogger<QobuzMetadataService> _logger;
-    private readonly GenreEnrichmentService _genreEnrichment;
+    private readonly GenreEnrichmentService? _genreEnrichment;
     private readonly string? _userAuthToken;
     private readonly string? _userId;
     
@@ -31,7 +31,7 @@ public class QobuzMetadataService : IMusicMetadataService
         IOptions<QobuzSettings> qobuzSettings,
         QobuzBundleService bundleService,
         ILogger<QobuzMetadataService> logger,
-        GenreEnrichmentService genreEnrichment)
+        GenreEnrichmentService? genreEnrichment = null)
     {
         _httpClient = httpClientFactory.CreateClient();
         _settings = settings.Value;
@@ -184,7 +184,7 @@ public class QobuzMetadataService : IMusicMetadataService
             var song = ParseQobuzTrackFull(track);
             
             // Enrich with MusicBrainz genres if missing
-            if (song != null && string.IsNullOrEmpty(song.Genre))
+            if (_genreEnrichment != null && song != null && string.IsNullOrEmpty(song.Genre))
             {
                 await _genreEnrichment.EnrichSongGenreAsync(song);
             }

allstarr/Services/SquidWTF/SquidWTFMetadataService.cs

@@ -56,7 +56,7 @@ public class SquidWTFMetadataService : IMusicMetadataService
     private readonly ILogger<SquidWTFMetadataService> _logger;
     private readonly RedisCacheService _cache;
     private readonly RoundRobinFallbackHelper _fallbackHelper;
-    private readonly GenreEnrichmentService _genreEnrichment;
+    private readonly GenreEnrichmentService? _genreEnrichment;
 
     public SquidWTFMetadataService(
         IHttpClientFactory httpClientFactory, 
@@ -65,7 +65,7 @@ public class SquidWTFMetadataService : IMusicMetadataService
         ILogger<SquidWTFMetadataService> logger,
         RedisCacheService cache,
         List<string> apiUrls,
-        GenreEnrichmentService genreEnrichment)
+        GenreEnrichmentService? genreEnrichment = null)
     {
         _httpClient = httpClientFactory.CreateClient();
         _settings = settings.Value;
@@ -290,7 +290,7 @@ public class SquidWTFMetadataService : IMusicMetadataService
 			var song = ParseTidalTrackFull(track);
 			
 			// Enrich with MusicBrainz genres if missing (SquidWTF/Tidal doesn't provide genres)
-			if (string.IsNullOrEmpty(song.Genre))
+			if (_genreEnrichment != null && string.IsNullOrEmpty(song.Genre))
 			{
 				await _genreEnrichment.EnrichSongGenreAsync(song);
 			}