feat: 添加图床归档任务支持，优化归档逻辑和错误处理

prisma/schema.prisma

@@ -19,6 +19,14 @@ enum ImageGenerationStatus {
   FAILED
 }
 
+enum ImageArchiveStatus {
+  NOT_REQUIRED
+  PENDING
+  RUNNING
+  SUCCEEDED
+  FAILED
+}
+
 model User {
   id               Int               @id
   username         String            @default("") @db.VarChar(191)
@@ -49,6 +57,12 @@ model ImageGeneration {
   upstreamResponse Json?                 @map("upstream_response")
   hostedResponse   Json?                 @map("hosted_response")
   errorMessage     String?               @map("error_message") @db.Text
+  archiveStatus    ImageArchiveStatus    @default(NOT_REQUIRED) @map("archive_status")
+  archiveAttempts  Int                   @default(0) @map("archive_attempts")
+  archiveNextRunAt DateTime?             @map("archive_next_run_at")
+  archiveLockedAt  DateTime?             @map("archive_locked_at")
+  archiveLockedBy  String?               @map("archive_locked_by") @db.VarChar(191)
+  archiveLastError String?               @map("archive_last_error") @db.Text
   createdAt        DateTime              @default(now()) @map("created_at")
   updatedAt        DateTime              @updatedAt @map("updated_at")
   deletedAt        DateTime?             @map("deleted_at")
@@ -56,6 +70,8 @@ model ImageGeneration {
 
   @@index([userId, createdAt])
   @@index([status])
+  @@index([archiveStatus, archiveNextRunAt])
+  @@index([archiveLockedAt])
   @@index([deletedAt])
   @@map("image_generations")
 }