fix(welfare): review 修复 — 里程碑"暂不发金币"文档同步 + 消息提醒奖励降为 1000

- comparison_milestone: 删 record_milestone_reward 死导入(ruff F401), 模块 docstring 同步"暂不发金币"
- 里程碑文档群对齐实现: compare-milestones / comparison_milestone_claim / MilestoneStateOut.coin 描述都标注暂不真发金币
- models/comparison: comparison_results JSONB 形状注释补 coupon_saved
- enable_notification 奖励 10000→1000(产品定, =¥0.1); test_exchange_flow 改 grant_coins 直接供款(不再靠该任务=兑换下限)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_welfare.py

@@ -12,6 +12,9 @@ from app.core.rewards import (
     TASK_ENABLE_NOTIFICATION,
     TASK_REWARDS,
 )
+from app.db.session import SessionLocal
+from app.repositories import wallet as crud_wallet
+from app.repositories.user import get_user_by_phone
 
 
 def _login(client, phone: str) -> str:
@@ -130,10 +133,19 @@ def test_exchange_info(client) -> None:
 
 
 def test_exchange_flow(client) -> None:
-    """先用任务领够金币 → 兑换 1 元 → 金币扣、现金加 → 现金流水有记录。"""
-    token = _login(client, "13800001005")
-    # 领"打开消息提醒"得 10000 金币(= 1 元额度)
-    client.post(f"/api/v1/tasks/{TASK_ENABLE_NOTIFICATION}/claim", headers=_auth(token))
+    """先供款够兑换下限的金币 → 兑换 1 元 → 金币扣、现金加 → 现金流水有记录。
+
+    打开消息提醒任务已降到 1000 金币(不再 = 兑换下限), 不能再靠领任务供款;
+    直接 grant_coins 注入 MIN_EXCHANGE_COIN(= COIN_PER_YUAN = 10000)当种子。
+    """
+    phone = "13800001005"
+    token = _login(client, phone)
+    # 供款: 直接注入 1 元额度金币(替代原先靠 notification=10000 领任务供款)
+    with SessionLocal() as db:
+        user = get_user_by_phone(db, phone)
+        assert user is not None
+        crud_wallet.grant_coins(db, user.id, MIN_EXCHANGE_COIN, biz_type="test_seed", remark="测试供款")
+        db.commit()
 
     # 兑换 10000 金币 → 100 分
     r = client.post(