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/organization.py

@@ -0,0 +1,165 @@
+"""
+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 func
+from sqlalchemy.orm import Session
+from typing import Optional, List
+from app.models.organization import Organization
+from app.core.logger import get_logger
+
+logger = get_logger(__name__)
+from uuid import UUID
+
+class OrganizationRepository:
+    def __init__(self, db: Session):
+        self.db = db
+
+    def create_organization(
+        self,
+        name: str,
+        domain: str,
+        timezone: str = 'UTC',
+        business_hours: Optional[dict] = None
+    ) -> Organization:
+        """Create a new organization"""
+        try:
+            organization = Organization(
+                name=name,
+                domain=domain,
+                timezone=timezone,
+                business_hours=business_hours
+            )
+            self.db.add(organization)
+            self.db.flush()  # Get organization.id
+            return organization
+
+        except Exception as e:
+            logger.error(f"Failed to create organization: {str(e)}")
+            self.db.rollback()
+            raise
+
+    def get_organization(self, org_id: UUID) -> Optional[Organization]:
+        """Get organization by ID"""
+        return self.db.query(Organization).filter(
+            Organization.id == org_id
+        ).first()
+
+    def get_organization_by_domain(self, domain: str) -> Optional[Organization]:
+        """Get organization by domain"""
+        return self.db.query(Organization).filter(
+            Organization.domain == domain
+        ).first()
+
+    def is_domain_taken(self, domain: str, exclude_org_id: Optional[UUID] = None) -> bool:
+        """Whether another organization already uses this domain, ignoring case"""
+        query = self.db.query(Organization.id).filter(
+            func.lower(Organization.domain) == domain.lower()
+        )
+        if exclude_org_id is not None:
+            query = query.filter(Organization.id != exclude_org_id)
+        return query.first() is not None
+
+    def get_active_organizations(self) -> List[Organization]:
+        """Get all active organizations"""
+        return self.db.query(Organization).filter(
+            Organization.is_active == True
+        ).all()
+
+    def update_organization(
+        self,
+        org_id: UUID,
+        name: Optional[str] = None,
+        domain: Optional[str] = None,
+        settings: Optional[dict] = None,
+        is_active: Optional[bool] = None
+    ) -> Optional[Organization]:
+        """Update an organization"""
+        try:
+            organization = self.get_organization(org_id)
+            if not organization:
+                return None
+
+            if name is not None:
+                organization.name = name
+            if domain is not None:
+                organization.domain = domain
+            if settings is not None:
+                # Merge into a NEW dict: the column default is a shared mutable
+                # {} and an in-place update is invisible to the unit of work
+                organization.settings = {**(organization.settings or {}), **settings}
+            if is_active is not None:
+                organization.is_active = is_active
+
+            self.db.commit()
+            self.db.refresh(organization)
+            return organization
+
+        except Exception as e:
+            logger.error(f"Failed to update organization {org_id}: {str(e)}")
+            self.db.rollback()
+            raise
+
+    def update_settings(self, org_id: UUID, settings: dict) -> Optional[Organization]:
+        """Update organization settings"""
+        try:
+            organization = self.get_organization(org_id)
+            if not organization:
+                return None
+
+            # Merge into a NEW dict (shared mutable default, see update_organization)
+            organization.settings = {**(organization.settings or {}), **settings}
+
+            self.db.commit()
+            self.db.refresh(organization)
+            return organization
+
+        except Exception as e:
+            logger.error(f"Failed to update settings for org {
+                         org_id}: {str(e)}")
+            self.db.rollback()
+            raise
+
+    def deactivate_organization(self, org_id: UUID) -> bool:
+        """Deactivate an organization"""
+        try:
+            organization = self.get_organization(org_id)
+            if not organization:
+                return False
+
+            organization.is_active = False
+            self.db.commit()
+            return True
+
+        except Exception as e:
+            logger.error(f"Failed to deactivate org {org_id}: {str(e)}")
+            self.db.rollback()
+            raise
+
+    def delete_organization(self, org_id: UUID) -> bool:
+        """Hard delete an organization (use with caution)"""
+        try:
+            organization = self.get_organization(org_id)
+            if not organization:
+                return False
+
+            self.db.delete(organization)
+            self.db.commit()
+            return True
+
+        except Exception as e:
+            logger.error(f"Failed to delete org {org_id}: {str(e)}")
+            self.db.rollback()
+            raise