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/models/task.py

@@ -119,7 +119,14 @@ class ImageCandidate(Base):
     strategy: Mapped[str | None] = mapped_column(String(4))    # A/B/C（二期）
     seq: Mapped[int] = mapped_column(Integer, default=1)        # 分镜序号
     is_selected: Mapped[bool] = mapped_column(default=False, nullable=False)
+    # R2 重生标记：True=用户手动重生产出(新增不删旧,前端同strategy+role默认只展示最新)
+    is_regen: Mapped[bool] = mapped_column(default=False, nullable=False)
     eval_score: Mapped[float | None] = mapped_column(Float)     # 一期留 NULL
+    # 标题文字校验结果JSON(NULL=通过;有值=曾不过/重生,前端提示运营人工筛)
+    text_review: Mapped[str | None] = mapped_column(String(512))
+    # AI评图分0-100(展示+生成时筛选+排序用,绝不进飞轮权重;eval_score 另留 NULL)
+    ai_visual_score: Mapped[float | None] = mapped_column(Float)
+    ai_visual_note: Mapped[str | None] = mapped_column(String(256))   # AI评图一句话评语(前端展示)
     created_at: Mapped[datetime] = mapped_column(
         DateTime, server_default=func.now(), nullable=False
     )