feat(meituan-coupon): 头图改为统一压缩(去掉大小阈值,全部拼缩放参数)

产品要求所有头图都压缩,不再按 image_size 阈值判定:
- feed_image_url 改为无条件给图片 URL 拼 @375w_375h_1e_1c.webp(缩 124dp + 转 WebP)
- 去掉 FEED_THUMB_SIZE_THRESHOLD 阈值常量;from_raw / 两处 DB 路不再传 image_size
- image_size/image_type 两列保留用于分析/监控(GIF 占比、体积分布),采集逻辑不变
- 文档更新:head_image_url 现统一带缩放参数

注:读取侧统一压缩,部署后即对全部 feed 图生效,无需依赖 image_size 回填。

app/api/v1/meituan.py

@@ -202,7 +202,7 @@ def feed(req: FeedRequest, db: Session = Depends(get_db)) -> FeedResponse:
         cards: list[CouponCard] = []
         for row in rows[:PAGE]:
             try:
-                card = CouponCard.from_raw(row.raw or {}, image_size=row.image_size)
+                card = CouponCard.from_raw(row.raw or {})
             except Exception:  # noqa: BLE001
                 continue
             if card.product_view_sign:
@@ -288,7 +288,7 @@ def top_sales(req: TopSalesRequest, db: Session = Depends(get_db)) -> CouponList
     cards: list[CouponCard] = []
     for row in rows[:req.page_size]:
         try:
-            card = CouponCard.from_raw(row.raw or {}, image_size=row.image_size)
+            card = CouponCard.from_raw(row.raw or {})
         except Exception:  # noqa: BLE001
             continue
         if card.product_view_sign: