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/repositories/channels/agent_config.py

@@ -0,0 +1,103 @@
+"""
+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 typing import Optional, List
+from uuid import UUID
+
+from sqlalchemy.orm import Session
+
+from app.models.channels import AgentChannelConfig
+from app.core.logger import get_logger
+
+logger = get_logger(__name__)
+
+
+class AgentChannelConfigRepository:
+    def __init__(self, db: Session):
+        self.db = db
+
+    def get_by_account(self, channel_account_id: UUID) -> Optional[AgentChannelConfig]:
+        try:
+            return self.db.query(AgentChannelConfig).filter(
+                AgentChannelConfig.channel_account_id == channel_account_id
+            ).first()
+        except Exception as e:
+            logger.error(f"Error getting agent channel config: {str(e)}")
+            return None
+
+    def get_active_agent_id(self, channel_account_id: UUID) -> Optional[UUID]:
+        """Agent that answers inbound messages on this account, if enabled."""
+        config = self.get_by_account(channel_account_id)
+        if config and config.is_active:
+            return config.agent_id
+        return None
+
+    def map_by_accounts(self, channel_account_ids: List[UUID]) -> dict:
+        """Configs for many accounts in one query, keyed by channel_account_id."""
+        if not channel_account_ids:
+            return {}
+        try:
+            configs = self.db.query(AgentChannelConfig).filter(
+                AgentChannelConfig.channel_account_id.in_(channel_account_ids)
+            ).all()
+            return {config.channel_account_id: config for config in configs}
+        except Exception as e:
+            logger.error(f"Error mapping agent channel configs: {str(e)}")
+            return {}
+
+    def list_by_agent(self, agent_id: UUID) -> List[AgentChannelConfig]:
+        try:
+            return self.db.query(AgentChannelConfig).filter(
+                AgentChannelConfig.agent_id == agent_id
+            ).all()
+        except Exception as e:
+            logger.error(f"Error listing agent channel configs: {str(e)}")
+            return []
+
+    def set_agent(self, channel_account_id: UUID, agent_id: UUID, is_active: bool = True) -> AgentChannelConfig:
+        """Upsert the single agent mapping for a channel account."""
+        try:
+            config = self.get_by_account(channel_account_id)
+            if config:
+                config.agent_id = agent_id
+                config.is_active = is_active
+            else:
+                config = AgentChannelConfig(
+                    channel_account_id=channel_account_id,
+                    agent_id=agent_id,
+                    is_active=is_active,
+                )
+                self.db.add(config)
+            self.db.commit()
+            self.db.refresh(config)
+            return config
+        except Exception as e:
+            logger.error(f"Error setting agent channel config: {str(e)}")
+            self.db.rollback()
+            raise
+
+    def delete_by_account(self, channel_account_id: UUID) -> bool:
+        try:
+            config = self.get_by_account(channel_account_id)
+            if not config:
+                return False
+            self.db.delete(config)
+            self.db.commit()
+            return True
+        except Exception as e:
+            logger.error(f"Error deleting agent channel config: {str(e)}")
+            self.db.rollback()
+            return False