提现档位后端权威化:tiers下发+每日限次/选一额度+下单档位闸(7-9) (#129)

## 提现档位后端权威化(7-9,配套 android 同名分支 PR)

### 规则(2026-07-09 与产品逐条拍板)
- 档位硬编码 `rewards.WITHDRAW_TIERS_COIN_CASH`:0.1/0.3(新人,历史一次性)+ 0.5(日3次)/10/20(日1次)
- 计次口径「发起就算」:当天创建的单不论最终状态(含被拒/失败)都占名额
- 新人档:任意状态发起过即永久消失;两档独立同天可各提一次;不参与「每日选一个额度」互斥
- 常规三档每天只能选一个;invite_cash 无档位概念(tiers 空、下单不走档位闸,邀请页行为不变)
- 「今天」= 北京时 cn_today();计次与 admin 看板同口径(Beijing 0点转 UTC 比较 created_at)

### 改动
- `GET /wallet/withdraw-info` 新增 `source` 参数 + 响应 `tiers[]`(amount/label/badge/available/disabled_reason/remaining_today)
- `create_withdraw` 加档位闸:coin_cash 仅可提预设档位且该档可提,否则 400/409(防绕过客户端刷);放在幂等返回/在途互斥之后,不破坏同号重试
- 0.01 调试直发(allow_sub_min)不受档位约束,保持原样

### 测试
- 新增 `tests/test_withdraw_tiers.py` 6 项全过(档位下发/新人独立+一次性/选一额度/次数耗尽/非档位金额拒绝/invite 不受影响)
- 全量回归 305 过;5 项失败为 main 既有(coupon_proxy/invite_compare_reward,stash 验证与本 PR 无关)
- 3 处旧测试的 coin_cash 金额从 100/200 调整为合法档位 50

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

---------

Co-authored-by: no_gen_mu <liujianhishen@gmail.com>
Reviewed-on: #129
Co-authored-by: liujiahui <liujiahui@wonderable.ai>
Co-committed-by: liujiahui <liujiahui@wonderable.ai>

tests/test_invite_cash_withdraw.py

@@ -143,14 +143,15 @@ def test_two_accounts_withdraw_independent(client, monkeypatch) -> None:
     _reject(r1.json()["out_bill_no"])    # 退回 invite_cash + 结清活跃单
     r2 = client.post(
         "/api/v1/wallet/withdraw",
-        json={"amount_cents": 100, "source": "coin_cash"},
+        # 50 分 = 0.5 元档(7-9 起 coin_cash 只能提预设档位)
+        json={"amount_cents": 50, "source": "coin_cash"},
         headers=_auth(token),
     )
     assert r2.json()["status"] == "reviewing"
 
     cash, invite_cash = _balances(client, token)
     assert invite_cash == 500    # 已退回
-    assert cash == 300           # 扣了 cash 100
+    assert cash == 350           # 扣了 cash 50
 
 
 def test_invite_me_returns_reward_stats(client) -> None:
@@ -177,7 +178,8 @@ def test_withdraw_orders_source_filter(client, monkeypatch) -> None:
     _reject(r1.json()["out_bill_no"])    # 结清,才能提第二笔
     client.post(
         "/api/v1/wallet/withdraw",
-        json={"amount_cents": 100, "source": "coin_cash"},
+        # 50 分 = 0.5 元档(7-9 起 coin_cash 只能提预设档位)
+        json={"amount_cents": 50, "source": "coin_cash"},
         headers=_auth(token),
     )