feat(wallet): 解绑微信前对待审核提现二次确认 (#46)

## 改动
解绑微信前若有**待审核(reviewing)**提现单,首次解绑被拦下返回二次确认,用户确认后带 `force=true` 才真解绑。

- `schemas`: `UnbindWechatRequest{force}` + `UnbindWechatResultOut{needs_confirm, message}`
- `repositories`: `has_reviewing_withdraw`(只看 reviewing)
- `api`: `unbind-wechat` 接受可选 body(兼容旧无 body 客户端);`bound` 返回真实绑定态
- `docs/api`: 同步协议

## 为什么只拦 reviewing
reviewing 单解绑后审核打款会回读空 openid → 自动退回现金(钱不丢、只为让用户知情);pending 转账已在途、解绑影响不到,不拦。

配套客户端见 shaguabijia-app-android 同名分支。

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

---------

Co-authored-by: OuYingJun1024 <1034284404@qq.com>
Reviewed-on: #46
Co-authored-by: ouzhou <ouzhou@wonderable.ai>
Co-committed-by: ouzhou <ouzhou@wonderable.ai>

alembic/versions/coin_transaction_task_ref_unique.py

@@ -0,0 +1,40 @@
+"""add coin_transaction task ref unique index
+
+可重复任务(task_enable_notification「打开消息提醒」逐次减半领取)的发放路径是无锁的
+读-算-写:并发/连点的两个 claim 会都读到同一已领次数、算出同一 ref_id(task_key:N)、
+各发一笔,导致双倍发钱。给 coin_transaction 加 (user_id, biz_type, ref_id) 部分唯一索引
+(仅 biz_type LIKE 'task%' 且 ref_id 非空),第二笔撞唯一约束 → IntegrityError,被
+task.claim_task 兜底成 AlreadyClaimedError(409)。与 cash_transaction 提现退款、
+withdraw_order 在途单的「唯一约束 + IntegrityError 兜底」同模式。
+
+Revision ID: coin_txn_task_ref_uq
+Revises: drop_force_onboarding
+Create Date: 2026-06-12 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = "coin_txn_task_ref_uq"
+down_revision: Union[str, Sequence[str], None] = "drop_force_onboarding"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_index(
+        "ux_coin_transaction_task_ref",
+        "coin_transaction",
+        ["user_id", "biz_type", "ref_id"],
+        unique=True,
+        sqlite_where=sa.text("biz_type LIKE 'task%' AND ref_id IS NOT NULL"),
+        postgresql_where=sa.text("biz_type LIKE 'task%' AND ref_id IS NOT NULL"),
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("ux_coin_transaction_task_ref", table_name="coin_transaction")