feat(cps): 淘宝活动落地页图做活——每活动关联图,运营上传/选已有

- model: cps_activity.image_url + 迁移 cps_activity_image 回填存量淘宝活动为现有图
- admin: 新建淘宝活动必传图(上传 /upload-image 或选已有 /activity-images),存绝对 URL
- 落地页 cps_redirect: 按 link→activity 取图展示,缺图兜底默认图,img src 经 html.escape
- media: save_cps_image + to_abs_media_url(基于 CPS_REDIRECT_BASE,跨域 admin-web 可显示)

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

alembic/versions/cps_activity_image.py

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+"""cps activity 落地页图: cps_activity.image_url + 回填存量淘宝活动
+
+新建淘宝活动时运营提供落地页主视觉图(上传或选已有),落地页按活动展示对应图。
+存量淘宝活动回填为此前写死的那张图,无缝衔接。
+
+Revision ID: cps_activity_image
+Revises: cps_v2_platforms
+Create Date: 2026-06-17 12:00:00.000000
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+from app.core.config import settings
+
+
+revision: str = "cps_activity_image"
+down_revision: Union[str, Sequence[str], None] = "cps_v2_platforms"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column("cps_activity", sa.Column("image_url", sa.String(512), nullable=True))
+    # 回填存量淘宝活动 = 此前写死的那张图(绝对 URL,基于落地页域名 CPS_REDIRECT_BASE;
+    # dev 未配则相对路径)。新活动由运营自传/选,不回填。
+    base = settings.CPS_REDIRECT_BASE.rstrip("/")
+    default_img = f"{base}/media/taobao_landing.jpg" if base else "/media/taobao_landing.jpg"
+    op.execute(
+        sa.text(
+            "UPDATE cps_activity SET image_url = :img WHERE platform = 'taobao'"
+        ).bindparams(img=default_img)
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("cps_activity", "image_url")