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

mini-program/app/models/entities.py

@@ -100,6 +100,8 @@ 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"))
@@ -126,7 +128,7 @@ class Card(Base):
 
     card_id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
     card_uuid: Mapped[str] = mapped_column(String(64), unique=True, nullable=False)
-    device_id: Mapped[Optional[str]] = mapped_column(String(64), unique=True)
+    device_id: Mapped[Optional[str]] = mapped_column(String(64))
     card_name: Mapped[Optional[str]] = mapped_column(String(64))
     status: Mapped[int] = mapped_column(Integer, server_default="0")
     total_swaps: Mapped[int] = mapped_column(Integer, server_default="0")