added Deluge label creation

code/Infrastructure/Verticals/DownloadClient/Deluge/DelugeClient.cs

@@ -1,4 +1,4 @@
-using System.Net.Http.Headers;
+using System.Net.Http.Headers;
 using System.Text.Json.Serialization;
 using Common.Configuration;
 using Common.Configuration.DownloadClient;
@@ -194,6 +194,16 @@ public sealed class DelugeClient
         return webResponse.Result;
     }
 
+    public async Task<IReadOnlyList<string>> GetLabels()
+    {
+        return await SendRequest<IReadOnlyList<string>>("label.label.get_labels");
+    }
+    
+    public async Task CreateLabel(string label)
+    {
+        await SendRequest<DelugeResponse<object>>("label.add", label);
+    }
+
     public async Task SetTorrentLabel(string hash, string newLabel)
     {
         // TODO

code/Infrastructure/Verticals/DownloadClient/Deluge/DelugeService.cs

@@ -298,7 +298,14 @@ public class DelugeService : DownloadService, IDelugeService
 
     public override async Task CreateCategoryAsync(string name)
     {
-        throw new NotImplementedException();
+        IReadOnlyList<string> existingLabels = await _client.GetLabels();
+
+        if (existingLabels.Contains(name, StringComparer.InvariantCultureIgnoreCase))
+        {
+            return;
+        }
+        
+        await _client.CreateLabel(name);
     }
 
     public override async Task ChangeCategoryForNoHardLinksAsync(List<object>? downloads, HashSet<string> excludedHashes, IReadOnlyList<string> ignoredDownloads)