feat(coin-history): 信息流广告奖励按点位场景拆流水文案(比价/领券) (#124)

## 改动
`grant_feed_reward` 按 `feed_scene` 落不同 `biz_type`/`remark`,让收益明细里比价等候期看的广告与领券时看的广告文案分开:

- `comparison` → `feed_ad_reward_comparison`(比价奖励)
- `coupon` → `feed_ad_reward_coupon`(领券奖励)
- 其余(welfare / 空 / 旧端不传)→ 维持通用 `feed_ad_reward`(信息流广告奖励)

客户端按 `biz_type` 直显固定文案(见 android 侧 `CoinHistoryViewModel.coinTitle`),`remark` 仅作后台留痕/兜底。

## 附:验收脚手架
`scripts/seed_coinhistory_labels_test.py`(dev-only):往测试号 `11111111111` 塞每种 bizType 各一条金币流水(`ref_id` 前缀 `TESTDOC`),一屏核对收益明细全部新文案;`--clean` 按前缀精确清理,不污染真实数据。

## 联动
客户端配套改动:`shaguabijia-app-android` 同名分支 `7-6ljh`。

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: no_gen_mu <liujianhishen@gmail.com>
Reviewed-on: #124
Co-authored-by: liujiahui <liujiahui@wonderable.ai>
Co-committed-by: liujiahui <liujiahui@wonderable.ai>

app/repositories/ad_feed_reward.py

@@ -176,10 +176,19 @@ def grant_feed_reward(
         )
         return _commit_record(db, rec, client_event_id)
 
+    # 按点位场景拆流水文案(2026-07):比价等候期看的广告 vs 领券时看的广告,在收益明细里分开显示。
+    # feed_scene=comparison→比价奖励 / coupon→领券奖励;其它(welfare/空/旧端不带)维持通用「信息流广告奖励」。
+    # 客户端按此 biz_type 直显固定文案(见 CoinHistoryViewModel.coinTitle),故 remark 只作后台留痕/兜底。
+    if feed_scene == "comparison":
+        reward_biz, reward_remark = "feed_ad_reward_comparison", "比价奖励"
+    elif feed_scene == "coupon":
+        reward_biz, reward_remark = "feed_ad_reward_coupon", "领券奖励"
+    else:
+        reward_biz, reward_remark = "feed_ad_reward", "信息流广告奖励"
     crud_wallet.grant_coins(
         db, user_id, coin,
-        biz_type="feed_ad_reward", ref_id=client_event_id,
-        remark="信息流广告奖励",
+        biz_type=reward_biz, ref_id=client_event_id,
+        remark=reward_remark,
     )
     rec = AdFeedRewardRecord(
         client_event_id=client_event_id,