feat(auth): 账号唯一性+清理多余账号 —— 迁移0011加phone/微信openid非空部分唯一索引

- users.phone/wx_openid/wx_mini_openid/wx_unionid 各自唯一(非空部分唯一索引)
- 创建账号必生成ID(create用new_id)；find_by_phone/find_by_wx 唯一校验
- cleanup_accounts.py 清理旧accounts已被users接管的重复账号；seed不再重复造账号、迁移后删旧行

app/infrastructure/repositories.py

@@ -219,6 +219,30 @@ class UserRepository:
         u = await self.session.get(User, user_id)
         return _user_to_dict(u) if u else None
 
+    async def find_by_phone(self, phone: str) -> dict | None:
+        """按已绑定手机号精准查找（唯一，非空；用户ID/登录名/手机号三者独立各唯一）。"""
+        p = (phone or "").strip()
+        if not p:
+            return None
+        u = await self.session.scalar(select(User).where(User.phone == p))
+        return _user_to_dict(u) if u else None
+
+    async def find_by_wx(self, *, openid: str = "", mini_openid: str = "") -> dict | None:
+        """按微信身份(网页开放平台 openid / 小程序 openid)查找用户。"""
+        if mini_openid:
+            u = await self.session.scalar(
+                select(User).where(User.wx_mini_openid == mini_openid.strip()),
+            )
+            if u:
+                return _user_to_dict(u)
+        if openid:
+            u = await self.session.scalar(
+                select(User).where(User.wx_openid == openid.strip()),
+            )
+            if u:
+                return _user_to_dict(u)
+        return None
+
     async def list(self) -> list[dict]:
         return [_user_to_dict(u) for u in await self.session.scalars(select(User).order_by(User.created_at))]