支持已绑定设备追加 NFC 卡

- 新增已绑定设备追加卡会话和小程序入口

- 允许同设备多张 active 卡，保留 card_uuid 唯一并补齐老库迁移

- 收紧未知卡自动绑定和跨设备卡复用

验证：talkingq-url/.venv/bin/python -m pytest tests；compileall；npm run build:weapp

talkingq-url/database/models.py

@@ -285,6 +285,8 @@ class DeviceBindSession(Base):
     max_attempt_count: Mapped[int] = mapped_column(Integer, server_default="5")
     attempt_count: Mapped[int] = mapped_column(Integer, server_default="0")
     status: Mapped[int] = mapped_column(Integer, server_default="1")
+    bind_mode: Mapped[int] = mapped_column(Integer, server_default="1")
+    card_uuid: Mapped[Optional[str]] = mapped_column(String(64))
     confirmed_at: Mapped[Optional[datetime]] = mapped_column(DateTime)
     consumed_at: Mapped[Optional[datetime]] = mapped_column(DateTime)
     created_at: Mapped[Optional[datetime]] = mapped_column(DateTime, server_default=text("CURRENT_TIMESTAMP"))