存量积累：生图素人感约束+评图分+幂等防重跑+审核回路

- 015-017迁移：image_candidate 文案复审/AI视觉分/重生标记
- constants C7素人感约束(反电商摆拍对齐真实笔记)+C3叠字口子
- celery visibility_timeout=2h 防长任务被误判重投重复烧钱(task75教训)
- image_scorer 评图分(只筛选+展示,真实信号才进飞轮权重)
- storyboard/image_gen/pipeline_io 生图存量
- task_actions/tasks/task_service/flywheel 审核回路+飞轮存量

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/services/task_service.py

@@ -79,8 +79,11 @@ def create_generation_task(
     return task
 
 
-def enqueue_generation(task_id: int) -> None:
-    """只推 task_id 入队，绝不推 key（基石B）。"""
+def enqueue_generation(task_id: int, regen_strategy: str | None = None,
+                       regen_role: str | None = None, custom_prompt: str | None = None) -> None:
+    """只推 task_id（+可选重生参数）入队，绝不推 key（基石B）。
+    regen_strategy/regen_role/custom_prompt 仅 R2 单张/单套重生时传，常规生成留 None。"""
     from app.workers.tasks import run_generation_pipeline
-    run_generation_pipeline.delay(task_id)
-    logger.info("Enqueued task_id=%s", task_id)
+    run_generation_pipeline.delay(task_id, regen_strategy=regen_strategy,
+                                  regen_role=regen_role, custom_prompt=custom_prompt)
+    logger.info("Enqueued task_id=%s regen=%s/%s", task_id, regen_strategy, regen_role)