feat(task-processor): implement PictureTaskProcessor for background image processing tasks

Models/DataBase/Picture.cs

@@ -41,10 +41,6 @@ public class Picture : BaseModel
 
     public bool ContentWarning { get; set; } = false;
     public PermissionType Permission { get; set; } = PermissionType.Public;
-
-    public ProcessingStatus ProcessingStatus { get; set; } = ProcessingStatus.Pending;
-    public string? ProcessingError { get; set; }
-    public int ProcessingProgress { get; set; } = 0;
 }
 
 public enum PermissionType
@@ -53,11 +49,3 @@ public enum PermissionType
     Friends = 1,
     Private = 2
 }
-
-public enum ProcessingStatus
-{
-    Pending, // 等待处理
-    Processing, // 处理中
-    Completed, // 处理完成
-    Failed // 处理失败
-}