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/rating.py

@@ -0,0 +1,97 @@
+"""
+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.orm import Session
+from app.models.rating import Rating
+from typing import Optional, List
+from uuid import UUID
+from sqlalchemy import func
+
+
+class RatingRepository:
+    def __init__(self, db: Session):
+        self.db = db
+
+    def create_rating(self, session_id: UUID, customer_id: UUID, user_id: UUID, agent_id: UUID, 
+                     organization_id: UUID, rating: int, feedback: Optional[str] = None) -> Rating:
+        """Create a new rating"""
+        db_rating = Rating(
+            session_id=session_id,
+            customer_id=customer_id,
+            user_id=user_id,
+            agent_id=agent_id,
+            organization_id=organization_id,
+            rating=rating,
+            feedback=feedback
+        )
+        self.db.add(db_rating)
+        self.db.commit()
+        self.db.refresh(db_rating)
+        return db_rating
+
+    def upsert_rating(self, session_id: UUID, customer_id: UUID, user_id: UUID, agent_id: UUID,
+                      organization_id: UUID, rating: int, feedback: Optional[str] = None) -> Rating:
+        """Record the customer's rating for a session, replacing any earlier one.
+
+        One row per session: the widget can re-show the rating prompt, and
+        without this a customer could pile up rows that skew agent/org averages
+        and, since the score now flows onto the ticket, spam its activity feed.
+        """
+        existing = self.get_rating_by_session(session_id)
+        if existing is None:
+            return self.create_rating(
+                session_id=session_id, customer_id=customer_id, user_id=user_id,
+                agent_id=agent_id, organization_id=organization_id,
+                rating=rating, feedback=feedback,
+            )
+        existing.rating = rating
+        existing.feedback = feedback
+        self.db.commit()
+        self.db.refresh(existing)
+        return existing
+
+    def get_rating_by_session(self, session_id: UUID) -> Optional[Rating]:
+        """Get rating by session ID"""
+        return self.db.query(Rating).filter(Rating.session_id == session_id).first()
+
+    def get_ratings_by_agent(self, agent_id: UUID) -> List[Rating]:
+        """Get all ratings for an agent"""
+        return self.db.query(Rating).filter(Rating.agent_id == agent_id).all()
+
+    def get_ratings_by_customer(self, customer_id: UUID) -> List[Rating]:
+        """Get all ratings from a customer"""
+        return self.db.query(Rating).filter(Rating.customer_id == customer_id).all()
+
+    def get_average_rating_by_agent(self, agent_id: UUID) -> float:
+        """Get average rating for an agent"""
+        result = self.db.query(func.avg(Rating.rating)).filter(
+            Rating.agent_id == agent_id
+        ).scalar()
+        return float(result) if result else 0.0
+
+    def get_organization_ratings(self, organization_id: UUID, 
+                               limit: int = 100, offset: int = 0) -> List[Rating]:
+        """Get all ratings for an organization with pagination"""
+        return self.db.query(Rating).filter(
+            Rating.organization_id == organization_id
+        ).order_by(Rating.created_at.desc()).offset(offset).limit(limit).all()
+
+    def get_organization_average_rating(self, organization_id: UUID) -> float:
+        """Get average rating for an organization"""
+        result = self.db.query(func.avg(Rating.rating)).filter(
+            Rating.organization_id == organization_id
+        ).scalar()
+        return float(result) if result else 0.0