feat: 今日模型使用统计返回模型图标信息

为 GetTodayModelUsage 接口补充模型图标数据，新增 ModelTodayUsageDto.IconUrl 字段
通过 ModelManager 查询已启用模型的 IconUrl 并映射到结果中
同时统一部分代码格式，提升可读性

Yi.Abp.Net8/module/ai-hub/Yi.Framework.AiHub.Domain/Managers/ModelManager.cs

@@ -11,7 +11,7 @@ namespace Yi.Framework.AiHub.Domain.Managers;
 /// </summary>
 public class ModelManager : DomainService
 {
-    private readonly ISqlSugarRepository<AiModelEntity> _aiModelRepository;
+    public readonly ISqlSugarRepository<AiModelEntity> _aiModelRepository;
     private readonly IDistributedCache<List<string>, string> _distributedCache;
     private readonly ILogger<ModelManager> _logger;
     private const string PREMIUM_MODEL_IDS_CACHE_KEY = "PremiumModelIds";