feat(wallet): 微信商家转账「用户授权免确认收款」(免确认到账) (#16)

提现从「每次跳微信确认」升级为免确认模式:首次授权一次,之后审核通过直接到账,用户零跳转。
方式一(首单转账顺带授权 pre-transfer-with-authorization)+ 方式二(显式开启 user-confirm-authorization)。

- 新增 wechat_transfer_authorization 表(user 1:1,out_authorization_no/authorization_id/state) + 迁移
- wxpay.py 新增 apply/query/close_transfer_authorization + pre_transfer_with_authorization + transfer_with_authorization
- repositories/wallet.py 授权 CRUD + sync/_refresh_active_auth + execute_withdraw_transfer 三分叉
  (active->免确认转账 / 无授权且配了回调->方式一 / 未配->退化原确认模式);失效回查授权权威判定,绝不盲退
- /wallet/transfer-auth(开启)/status/close 路由 + withdraw-info 增 transfer_auth_enabled
- 授权结果回调 stub /api/v1/wxpay/transfer-auth-notify(一期仅应答不验签,真值靠 query 轮询)
- config 增 WXPAY_AUTH_NOTIFY_URL

一期无回调验签;二期补 V3 平台证书验签 + AEAD 解密。

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

Reviewed-on: #16

app/main.py

@@ -29,6 +29,7 @@ from app.api.v1.signin import router as signin_router
 from app.api.v1.tasks import router as tasks_router
 from app.api.v1.user import router as user_router
 from app.api.v1.wallet import router as wallet_router
+from app.api.v1.wxpay import router as wxpay_router
 from app.core.config import settings
 from app.core.logging import setup_logging
 
@@ -82,6 +83,7 @@ app.include_router(compare_record_router)
 app.include_router(compare_milestone_router)
 app.include_router(meituan_router)
 app.include_router(wallet_router)
+app.include_router(wxpay_router)
 app.include_router(signin_router)
 app.include_router(tasks_router)
 app.include_router(savings_router)