feat: complete chat sessions and production startup

backend/wisegrade/models.py

@@ -292,7 +292,8 @@ class IndexTask(Base):
 class Conversation(Base):
     __tablename__ = "conversations"
     id = Column(Integer, primary_key=True)
-    title = Column(String(200), nullable=False, default="新对话")
+    title = Column(String(200), nullable=False, default="新会话")
+    first_request_id = Column(String(36), nullable=True, unique=True)
     course_version_id = Column(Integer, ForeignKey("course_versions.id"), nullable=True)
     batch_id = Column(Integer, ForeignKey("scoring_batches.id"), nullable=True)
     project_id = Column(Integer, ForeignKey("projects.id"), nullable=True)
@@ -317,6 +318,8 @@ class AgentRun(Base):
     conversation_id = Column(Integer, ForeignKey("conversations.id"), nullable=False)
     status = Column(String(30), nullable=False, default="running")
     error = Column(Text, default="")
+    tool_calls = Column(JSON, nullable=False, default=list)
+    events = Column(JSON, nullable=False, default=list)
     created_at = Column(DateTime(timezone=True), default=now)
     finished_at = Column(DateTime(timezone=True), nullable=True)