智教助手平台：完整初始化

- 前端：Vue3 + TS + Element Plus，24 个页面路由（课件/组题/教案/动画/思维导图/作文批改/命题/课堂/资源/社区等）
- 后端：FastAPI + SQLAlchemy + SQLite，17 个路由模块，AI 服务层含降级模板
- AI：glm-5.x 推理模型已禁用思维链，确保输出真实内容
- 修复：ai_service 两处请求体注入 enable_thinking/thinking disabled
- 测试账号：13900999999 / test1234

backend/models/chat.py

@@ -0,0 +1,39 @@
+from sqlalchemy import Column, Integer, String, DateTime, JSON, ForeignKey, Text, Boolean
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+from database import Base
+
+
+class ChatConversation(Base):
+    __tablename__ = "chat_conversations"
+
+    id = Column(Integer, primary_key=True, index=True)
+    user_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True)
+    title = Column(String(200), nullable=False, default="新对话")
+    subject = Column(String(50), default="")
+    grade = Column(String(50), default="")
+    pinned = Column(Boolean, default=False)
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())
+
+    author = relationship("User", back_populates="chat_conversations")
+    messages = relationship(
+        "ChatMessage",
+        back_populates="conversation",
+        order_by="ChatMessage.id",
+        lazy="selectin",
+        cascade="all, delete-orphan",
+    )
+
+
+class ChatMessage(Base):
+    __tablename__ = "chat_messages"
+
+    id = Column(Integer, primary_key=True, index=True)
+    conversation_id = Column(Integer, ForeignKey("chat_conversations.id"), nullable=False, index=True)
+    role = Column(String(20), nullable=False)  # user / assistant / system
+    content = Column(Text, nullable=False)
+    tokens = Column(Integer, default=0)
+    created_at = Column(DateTime, server_default=func.now())
+
+    conversation = relationship("ChatConversation", back_populates="messages")