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/knowledge_queue.py

@@ -0,0 +1,68 @@
+"""
+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, Integer, String, JSON, DateTime, Enum, ForeignKey, Float, Index
+from sqlalchemy.sql import func
+from sqlalchemy.orm import relationship
+from app.database import Base
+import enum
+from sqlalchemy.dialects.postgresql import UUID
+
+class QueueStatus(str, enum.Enum):
+    PENDING = "pending"
+    PROCESSING = "processing"
+    COMPLETED = "completed"
+    FAILED = "failed"
+
+class ProcessingStage(str, enum.Enum):
+    NOT_STARTED = "not_started"
+    CRAWLING = "crawling"
+    EMBEDDING = "embedding"
+    COMPLETED = "completed"
+
+
+class KnowledgeQueue(Base):
+    __tablename__ = "knowledge_queue"
+    # The plan's source limit counts the crawls still in flight, so this is
+    # read on every add.
+    __table_args__ = (
+        Index("ix_knowledge_queue_org_status", "organization_id", "status"),
+    )
+
+    id = Column(Integer, primary_key=True, index=True)
+    organization_id = Column(UUID(as_uuid=True), nullable=False)
+    agent_id = Column(UUID(as_uuid=True), nullable=True)
+    user_id = Column(UUID(as_uuid=True), ForeignKey("users.id"), nullable=True)  # Nullable for Shopify session token auth
+    # 'pdf_file', 'pdf_url', 'website'
+    source_type = Column(String, nullable=False)
+    source = Column(String, nullable=False)  # File path or URL
+    status = Column(String, default=QueueStatus.PENDING)
+    error = Column(String, nullable=True)
+    # Renamed from metadata to queue_metadata
+    queue_metadata = Column(JSON, nullable=True)
+    # Priority: higher number = higher priority (default 0, explore URLs get 10)
+    priority = Column(Integer, default=0, index=True)
+    # Progress tracking
+    processing_stage = Column(String, default=ProcessingStage.NOT_STARTED)
+    progress_percentage = Column(Float, default=0.0)
+    total_items = Column(Integer, default=0)
+    processed_items = Column(Integer, default=0)
+    crawled_urls = Column(JSON, default=lambda: [])
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+
+    # Add relationship
+    user = relationship("User", back_populates="knowledge_queue_items")