Ollama doesn't support image generation

Deleted the OllamaImageGenerations constant from ServiceConstants as it is no longer used. Also, set the Ollama backend to null in ImageGenServiceFactory and cleaned up unused usings in ImageGenService.cs.

Author: Madzionator

src/MaIN.Services/Constants/ServiceConstants.cs

@@ -43,7 +43,6 @@ public static class ApiUrls
         public const string XaiOpenAiChatCompletions = "https://api.x.ai/v1/chat/completions";
         public const string XaiModels = "https://api.x.ai/v1/models";
 
-        public const string OllamaImageGenerations = "https://ollama.com/v1/images/generations";
         public const string OllamaOpenAiChatCompletions = "https://ollama.com/v1/chat/completions";
         public const string OllamaModels = "https://ollama.com/v1/models";
     }

src/MaIN.Services/Services/ImageGenServices/ImageGenService.cs

@@ -1,7 +1,3 @@
-using System;
-using System.Linq;
-using System.Net.Http;
-using System.Threading.Tasks;
 using MaIN.Domain.Configuration;
 using MaIN.Domain.Entities;
 using MaIN.Services.Constants;

src/MaIN.Services/Services/LLMService/Factory/ImageGenServiceFactory.cs

@@ -20,6 +20,7 @@ public class ImageGenServiceFactory(IServiceProvider serviceProvider) : IImageGe
             BackendType.Anthropic => null,
             BackendType.Xai => new XaiImageGenService(serviceProvider.GetRequiredService<IHttpClientFactory>(),
                 serviceProvider.GetRequiredService<MaINSettings>()),
+            BackendType.Ollama => null,
             BackendType.Self => new ImageGenService(serviceProvider.GetRequiredService<IHttpClientFactory>(),
                 serviceProvider.GetRequiredService<MaINSettings>()),