feat: 用户表添加selected_audio_id字段，添加用户音频绑定接口

app/models/models.py

@@ -36,6 +36,7 @@ class User(Base):
     avatar_id = Column(String(36), nullable=True)
     tags = Column(JSON)
     persona = Column(JSON)
+    selected_audio_id = Column(Integer, nullable=True)
 
     def __repr__(self):
         return f"<User(id={self.id}, tags={self.tags})>"
@@ -81,6 +82,7 @@ class Session(Base):
     def __repr__(self):
         return f"<Session(id={self.id}, user_character_id={self.user_character_id})>"
 
+#音频表定义
 class Audio(Base):
     __tablename__ = 'audio'
     id = Column(Integer, primary_key=True, autoincrement=True)