fix(worker): viral_video Celery 任务改用 @shared_task，修复单测在 CI 下 resume_viral_video_pipeline.run 找不到的问题

- @celery_app.task 在 conftest mock Task.delay 之后若模块重新加载，decorator 返回的是未绑定原函数而非 Task 实例，导致 .run 方法不存在
- @shared_task（和 lipsync_tts.py 保持一致）在任务被任意 Celery app 加载时自动绑定，测试和生产环境行为一致
- 保留 celery_app import 为 noqa F401，确保 worker_app.celery_app 模块加载时会注册 viral_video tasks

apps/worker/worker_app/tasks/viral_video.py

@@ -19,9 +19,9 @@ from __future__ import annotations
 import logging
 import os
 
-from celery import Task
+from celery import Task, shared_task
 from celery.exceptions import Retry
-from worker_app.celery_app import celery_app
+from worker_app.celery_app import celery_app  # noqa: F401 - 加载 app 以注册任务
 from worker_app.db import SessionLocal
 
 from packages.adapters.sqlalchemy_impl.viral_video_repository import (
@@ -379,7 +379,7 @@ def _step_upload(job: ViralVideoJob, video_path: str) -> str:
 # ── 主编排器 ────────────────────────────────────────────────────────────
 
 
-@celery_app.task(bind=True, max_retries=2, name="worker.run_viral_video_pipeline")
+@shared_task(bind=True, max_retries=2, name="worker.run_viral_video_pipeline")
 def run_viral_video_pipeline(self: Task, job_id: str) -> dict:
     """爆款视频 10 步流水线编排器。"""
     session = None
@@ -452,7 +452,7 @@ def run_viral_video_pipeline(self: Task, job_id: str) -> dict:
             session.close()
 
 
-@celery_app.task(bind=True, max_retries=2, name="worker.resume_viral_video_pipeline")
+@shared_task(bind=True, max_retries=2, name="worker.resume_viral_video_pipeline")
 def resume_viral_video_pipeline(self: Task, job_id: str) -> dict:
     """用户确认意图后，从断点恢复流水线（步骤 3-10）。"""
     session = None
@@ -539,7 +539,7 @@ def resume_viral_video_pipeline(self: Task, job_id: str) -> dict:
             session.close()
 
 
-@celery_app.task(bind=True, max_retries=1, name="worker.run_video_style_analysis")
+@shared_task(bind=True, max_retries=1, name="worker.run_video_style_analysis")
 def run_video_style_analysis(self: Task, job_id: str) -> dict:
     """独立的视频风格分析任务（v1.3）。"""
     session = None