feat(models): 组织、用户、角色、客户、会话与消息模型

按组织边界定义数据关系，补齐仓储层与通用工具，迁移脚本可重复执行。

backend/app/models/shopify/agent_shopify_config.py

@@ -0,0 +1,36 @@
+"""
+Copyright 2024-2026 ReplyPier
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from sqlalchemy import Column, String, Boolean, DateTime, ForeignKey
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+from app.database import Base
+
+
+class AgentShopifyConfig(Base):
+    """Model for storing agent-to-Shopify configuration."""
+    __tablename__ = "agent_shopify_configs"
+
+    id = Column(String, primary_key=True)
+    agent_id = Column(String, nullable=False, index=True)
+    
+    # Link to ShopifyShop
+    shop_id = Column(String, ForeignKey("shopify_shops.id"), nullable=True)
+    shop = relationship("ShopifyShop", backref="agent_configs")
+    
+    enabled = Column(Boolean, default=False, nullable=False)
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())