feat(backend): update database models and add agent_conversation

- base.py: update database base configuration
- models/__init__.py: update models exports
- models/system_setting.py: update system setting model
- models/agent_conversation.py: add new agent conversation model

server/src/app/models/agent_conversation.py

@@ -0,0 +1,58 @@
+from __future__ import annotations
+
+import uuid
+from datetime import datetime
+from typing import Any
+
+from sqlalchemy import DateTime, ForeignKey, Integer, String, Text, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.types import JSON
+
+from app.db.base_class import Base
+
+
+class AgentConversation(Base):
+    __tablename__ = "agent_conversations"
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    conversation_id: Mapped[str] = mapped_column(String(50), unique=True, index=True)
+    user_id: Mapped[str | None] = mapped_column(String(100), nullable=True, index=True)
+    source: Mapped[str | None] = mapped_column(String(30), nullable=True, index=True)
+    entry_source: Mapped[str | None] = mapped_column(String(50), nullable=True)
+    title: Mapped[str | None] = mapped_column(String(200), nullable=True)
+    last_run_id: Mapped[str | None] = mapped_column(String(50), nullable=True, index=True)
+    last_scenario: Mapped[str | None] = mapped_column(String(50), nullable=True)
+    last_intent: Mapped[str | None] = mapped_column(String(50), nullable=True)
+    draft_claim_id: Mapped[str | None] = mapped_column(String(36), nullable=True, index=True)
+    state_json: Mapped[dict[str, Any]] = mapped_column(JSON, default=dict)
+    message_count: Mapped[int] = mapped_column(Integer, default=0)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+    )
+
+    messages = relationship(
+        "AgentConversationMessage",
+        back_populates="conversation",
+        cascade="all, delete-orphan",
+        order_by="asc(AgentConversationMessage.created_at)",
+    )
+
+
+class AgentConversationMessage(Base):
+    __tablename__ = "agent_conversation_messages"
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    conversation_id: Mapped[str] = mapped_column(
+        ForeignKey("agent_conversations.conversation_id"),
+        index=True,
+    )
+    run_id: Mapped[str | None] = mapped_column(String(50), nullable=True, index=True)
+    role: Mapped[str] = mapped_column(String(20), index=True)
+    content: Mapped[str] = mapped_column(Text())
+    message_json: Mapped[dict[str, Any]] = mapped_column(JSON, default=dict)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+
+    conversation = relationship("AgentConversation", back_populates="messages")