feat(invite): 邀请奖励金账户(与金币隔离) + 比价发奖 + 奖励金提现

- 新增邀请奖励金独立账本: coin_account 加余额列 + invite_cash_transaction 流水表, 与金币现金物理隔离
- bind 改 v2: 绑定只发被邀请人新人金币; 邀请人改在好友首次成功比价时发 2 元奖励金(幂等只发一次)
- 提现链路按 source 分流: 扣款/退款/对账/分页各认账户, 两本账不串
- /invite/me 返回奖励金余额/累计提现/7天倒计时
- 新增 migration(建表加列) + 比价发奖与提现隔离测试

app/models/wallet.py

@@ -25,6 +25,11 @@ class CoinAccount(Base):
     )
     coin_balance: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
     cash_balance_cents: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    # 邀请奖励金余额(分)——与金币兑换来的 cash_balance_cents **物理隔离**(产品红线:
+    # 邀请奖励金 ≠ 看广告/金币现金,两本账不可累加)。好友比价发奖入账、提现出账走它。
+    invite_cash_balance_cents: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=0, server_default="0"
+    )
     # 累计赚取的金币(只增不减),用于"历史总收益"类展示
     total_coin_earned: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
 
@@ -108,6 +113,11 @@ class WithdrawOrder(Base):
     # 商户单号(我们生成,微信查单的 out_bill_no),唯一
     out_bill_no: Mapped[str] = mapped_column(String(64), unique=True, index=True, nullable=False)
     amount_cents: Mapped[int] = mapped_column(Integer, nullable=False)
+    # 这笔提现扣的是哪个账户:coin_cash(金币兑换的现金) / invite_cash(邀请奖励金)。
+    # 退款时据此退回**对应**账户,两本账不串。旧单默认 coin_cash。
+    source: Mapped[str] = mapped_column(
+        String(16), nullable=False, default="coin_cash", server_default="coin_cash"
+    )
     # 提现实名(微信达额转账要求):审核后异步打款时要用,发起提现时存下,可空
     user_name: Mapped[str | None] = mapped_column(String(64), nullable=True)
     # 归一化状态:reviewing(待审核) / pending(打款在途) / success / failed(打款失败已退) / rejected(审核拒绝已退)
@@ -200,3 +210,41 @@ class CashTransaction(Base):
 
     def __repr__(self) -> str:  # pragma: no cover
         return f"<CashTransaction id={self.id} user_id={self.user_id} cents={self.amount_cents}>"
+
+
+class InviteCashTransaction(Base):
+    """邀请奖励金流水(单位:分)。与 cash_transaction(金币兑换现金)**物理隔离**——
+    产品红线:邀请奖励金 ≠ 看广告/金币现金,两本账不可累加、各自提现。
+    入账=好友比价发奖(invite_reward),出账=提现(invite_withdraw)/退款(invite_withdraw_refund)。
+    结构与 cash_transaction 同构,balance_after_cents 记的是 coin_account.invite_cash_balance_cents。"""
+
+    __tablename__ = "invite_cash_transaction"
+    __table_args__ = (
+        # 提现退款幂等:一个提现单只退一次(同 cash_transaction 的 withdraw_refund 去重)
+        Index(
+            "ux_invite_cash_txn_refund_ref",
+            "ref_id",
+            unique=True,
+            sqlite_where=text("biz_type = 'invite_withdraw_refund' AND ref_id IS NOT NULL"),
+            postgresql_where=text("biz_type = 'invite_withdraw_refund' AND ref_id IS NOT NULL"),
+        ),
+    )
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    user_id: Mapped[int] = mapped_column(
+        Integer, ForeignKey("user.id"), index=True, nullable=False
+    )
+    # 正数=入账(发奖),负数=出账(提现)
+    amount_cents: Mapped[int] = mapped_column(Integer, nullable=False)
+    balance_after_cents: Mapped[int] = mapped_column(Integer, nullable=False)
+    # 业务类型:invite_reward / invite_withdraw / invite_withdraw_refund
+    biz_type: Mapped[str] = mapped_column(String(32), nullable=False)
+    ref_id: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    remark: Mapped[str | None] = mapped_column(String(128), nullable=True)
+
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), index=True, nullable=False
+    )
+
+    def __repr__(self) -> str:  # pragma: no cover
+        return f"<InviteCashTransaction id={self.id} user_id={self.user_id} cents={self.amount_cents}>"