feat: 素材重复上传检测 + 批量生成视频

任务1: 素材重复上传检测
- 上传接口支持 file_hash 参数，通过 MD5+素材库ID 去重
- 命中去重直接返回已有 asset_id，不重复存 OSS
- file_hash 透传: API → IngestJob → Asset 全链路
- 三条上传路径（表单/直传/分片）均支持去重
- Alembic 031: assets + ingest_jobs 加 file_hash 列+索引
- 6 个单元测试覆盖去重命中/未命中/空hash/透传

任务3: 批量生成视频
- POST /generations 支持 count 参数，一次创建多条生成任务
- 每条任务独立状态跟踪，响应返回 task_ids 列表

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/adapters/sqlalchemy_impl/asset_repository.py

@@ -83,6 +83,7 @@ class SQLAlchemyAssetRepository:
             classification_result=(json.dumps(asset.metadata) if asset.metadata else None),
             quality_score=asset.quality_score,
             uploaded_by_user_id=asset.uploaded_by_user_id or "system",
+            file_hash=asset.file_hash or None,
             created_at=asset.created_at,
             updated_at=now,
         )
@@ -110,6 +111,7 @@ class SQLAlchemyAssetRepository:
         model.classification_result = json.dumps(asset.metadata) if asset.metadata else None
         model.quality_score = asset.quality_score
         model.uploaded_by_user_id = asset.uploaded_by_user_id or model.uploaded_by_user_id
+        model.file_hash = asset.file_hash or model.file_hash
         model.updated_at = datetime.now(timezone.utc)
         self.session.flush()
         self._sync_asset_tags(asset.id, asset.tag_ids)
@@ -230,6 +232,7 @@ class SQLAlchemyAssetRepository:
             classification_status=ClassificationStatus(model.classification_status),
             quality_score=model.quality_score,
             uploaded_by_user_id=model.uploaded_by_user_id,
+            file_hash=model.file_hash or "",
             metadata=metadata,
             tag_ids=tag_ids,
             created_at=model.created_at,
@@ -267,3 +270,23 @@ class SQLAlchemyAssetRepository:
             return []
         models = self.session.query(AssetModel).filter(AssetModel.id.in_(ids)).offset(skip).limit(limit).all()
         return [self._to_domain(m) for m in models]
+
+    def find_by_library_and_file_hash(
+        self,
+        library_id: str,
+        file_hash: str,
+    ) -> Asset | None:
+        """按素材库 + 文件哈希查找已有素材（去重检测）。"""
+        if not file_hash:
+            return None
+        model = (
+            self.session.query(AssetModel)
+            .filter(
+                AssetModel.asset_library_id == library_id,
+                AssetModel.file_hash == file_hash,
+            )
+            .first()
+        )
+        if model is None:
+            return None
+        return self._to_domain(model)

packages/adapters/sqlalchemy_impl/ingest_job_repository.py

@@ -17,6 +17,7 @@ class SQLAlchemyIngestJobRepository:
             status=job.status.value,
             error_message=job.error_message,
             result_asset_id=job.result_asset_id,
+            file_hash=job.file_hash,
             created_at=job.created_at,
             updated_at=job.updated_at,
         )
@@ -36,6 +37,7 @@ class SQLAlchemyIngestJobRepository:
             status=IngestJobStatus(model.status),
             error_message=model.error_message,
             result_asset_id=model.result_asset_id,
+            file_hash=model.file_hash or "",
             created_at=model.created_at,
             updated_at=model.updated_at,
         )
@@ -51,6 +53,7 @@ class SQLAlchemyIngestJobRepository:
         model.status = job.status.value
         model.error_message = job.error_message
         model.result_asset_id = job.result_asset_id
+        model.file_hash = job.file_hash
         model.updated_at = job.updated_at
         self.session.commit()
         return job

packages/adapters/sqlalchemy_impl/models.py

@@ -85,6 +85,7 @@ class AssetModel(Base):
     classification_result = Column(Text, nullable=True)
     quality_score = Column(Float, nullable=True)
     uploaded_by_user_id = Column(String(36), nullable=False)
+    file_hash = Column(String(64), nullable=True, index=True)
     extra_meta = Column("metadata", JSON, nullable=False, default=dict)
     created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc), index=True)
     updated_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
@@ -210,6 +211,7 @@ class IngestJobModel(Base):
     status = Column(String(20), nullable=False, default="pending")
     error_message = Column(Text, nullable=False, default="")
     result_asset_id = Column(String(32), nullable=False, default="")
+    file_hash = Column(String(64), nullable=True, index=True)
     created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
     updated_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))