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/knowledge_queue.py

@@ -0,0 +1,149 @@
+"""
+Copyright 2024-2026 ChatterMate
+
+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 app.models.knowledge_queue import KnowledgeQueue, QueueStatus
+from typing import List, Optional
+from datetime import datetime
+from app.core.logger import get_logger
+from app.core.logger import get_logger
+
+logger = get_logger(__name__)
+
+
+class KnowledgeQueueRepository:
+    def __init__(self, db: Session):
+        self.db = db
+
+    def create(self, queue_item: KnowledgeQueue) -> KnowledgeQueue:
+        self.db.add(queue_item)
+        self.db.commit()
+        self.db.refresh(queue_item)
+        return queue_item
+
+    def get_by_id(self, queue_id: int) -> Optional[KnowledgeQueue]:
+        """Get queue item by ID"""
+        return self.db.query(KnowledgeQueue).filter(
+            KnowledgeQueue.id == queue_id
+        ).first()
+
+    def get_pending(self) -> List[KnowledgeQueue]:
+        """Get all pending queue items ordered by priority (highest first), then by creation time"""
+        return self.db.query(KnowledgeQueue)\
+            .filter(KnowledgeQueue.status == QueueStatus.PENDING)\
+            .order_by(KnowledgeQueue.priority.desc(), KnowledgeQueue.created_at.asc())\
+            .all()
+
+    def get_abandoned(self, last_progress_before: datetime) -> List[KnowledgeQueue]:
+        """Items still 'processing' with no progress since `last_progress_before`,
+        locked so two workers never handle the same one."""
+        return self.db.query(KnowledgeQueue)\
+            .filter(KnowledgeQueue.status == QueueStatus.PROCESSING,
+                    func.coalesce(KnowledgeQueue.updated_at, KnowledgeQueue.created_at) < last_progress_before)\
+            .with_for_update(skip_locked=True)\
+            .all()
+
+    def update_status(self, queue_id: int, status: QueueStatus, error: Optional[str] = None) -> bool:
+        item = self.db.query(KnowledgeQueue).filter(
+            KnowledgeQueue.id == queue_id).first()
+        if item:
+            item.status = status
+            item.error = error
+            # Update processing stage to COMPLETED when status is COMPLETED
+            if status == QueueStatus.COMPLETED:
+                item.processing_stage = "COMPLETED"
+                item.progress_percentage = 100.0
+            self.db.commit()
+            return True
+        return False
+        
+    def update_progress(
+        self, 
+        queue_id: int, 
+        processing_stage: str = None, 
+        progress_percentage: float = None,
+        total_items: int = None,
+        processed_items: int = None,
+        crawled_url: str = None,
+        force_stage_update: bool = False
+    ) -> bool:
+        """Update the progress of a queue item"""
+        item = self.db.query(KnowledgeQueue).filter(
+            KnowledgeQueue.id == queue_id).first()
+        if item:
+            # Define stage priority to prevent regression
+            stage_priority = {
+                "not_started": 0,
+                "crawling": 1,
+                "embedding": 2,
+                "completed": 3
+            }
+            
+            # Only update processing stage if it's an advancement or forced
+            if processing_stage and (force_stage_update or not item.processing_stage or 
+                stage_priority.get(processing_stage.lower(), 0) >= stage_priority.get(item.processing_stage.lower(), 0)):
+                item.processing_stage = processing_stage
+            
+            # Update progress percentage using main columns
+            if progress_percentage is not None:
+                item.progress_percentage = progress_percentage
+            elif processed_items is not None and total_items is not None and total_items > 0:
+                # Auto-calculate percentage based on processed/total items
+                item.progress_percentage = (processed_items / total_items) * 100
+                
+            if total_items is not None:
+                item.total_items = total_items
+                
+            if processed_items is not None:
+                item.processed_items = processed_items
+            
+            # Add crawled URL to the list if provided (store only URL strings)
+            if crawled_url:
+                if not item.crawled_urls:
+                    item.crawled_urls = []
+                # Store only the URL string, no timestamp or status
+                if crawled_url not in item.crawled_urls:
+                    # Create a new list to ensure SQLAlchemy detects the change
+                    new_crawled_urls = list(item.crawled_urls) if item.crawled_urls else []
+                    new_crawled_urls.append(crawled_url)
+                    item.crawled_urls = new_crawled_urls
+                    
+                    # Mark the attribute as modified to ensure SQLAlchemy commits the change
+                    from sqlalchemy.orm.attributes import flag_modified
+                    flag_modified(item, 'crawled_urls')
+                    
+                    from app.core.logger import get_logger
+                    logger = get_logger(__name__)
+                    logger.debug(f"📝 Added crawled URL to queue {queue_id}: {crawled_url} (total: {len(item.crawled_urls)})")
+                    
+                else:
+                    from app.core.logger import get_logger
+                    logger = get_logger(__name__)
+                    logger.debug(f"🔄 URL already in list for queue {queue_id}: {crawled_url}")
+                    
+            # Commit changes and verify
+            self.db.commit()
+            
+            # If we added a crawled URL, verify it was saved
+            if crawled_url:
+                self.db.refresh(item)
+                from app.core.logger import get_logger
+                logger = get_logger(__name__)
+                logger.debug(f"🔍 After commit - queue {queue_id} crawled_urls count: {len(item.crawled_urls) if item.crawled_urls else 0}")
+            
+            return True
+        return False