feat(ai): 重构AI聊天模块，使用agno框架替代langchain

- 移除langchain相关依赖，引入agno作为大模型开发框架
- 重构聊天会话和消息存储，使用agno的TeamSession管理
- 合并chat_message和chat_session模块为统一的chat模块
- 更新前端API和类型定义，适配新的后端接口
- 优化数据库日志字段类型，根据数据库类型自动选择
- 重构AI助手组件，使用新的聊天API
- 清理不再使用的模型、控制器和服务代码

backend/app/plugin/module_ai/chat/utils.py

@@ -0,0 +1,62 @@
+from typing import Any
+
+from agno.agent import Agent
+from agno.models.openai.like import OpenAILike
+from agno.team import Team
+
+from app.config.setting import settings
+
+
+class AgnoFactory:
+    """Agno 工厂类 - 统一管理 Agent、Team 创建逻辑"""
+    # 配置常量
+    AGENT_DESCRIPTION = "你是一个有用的AI助手，可以帮助用户回答问题和提供帮助。"
+    AGENT_INSTRUCTIONS = ["保持回答简洁明了", "如果不确定，请说明"]
+    AGENT_EXPECTED_OUTPUT = "中文回答"
+    AGENT_TEMPERATURE = 0.7
+    NUM_HISTORY_RUNS = 3
+
+    def create_agent(
+        self,
+        user_id: str,
+        dept_id: str,
+        session_id: str,
+        db: Any | None = None
+    ) -> Team:
+        """创建 Team 实例"""
+
+        # 创建 Agent
+        fastapiadmin_agent = Agent(
+            id=user_id,
+            name="fastapiadmin_agent",
+            role="You are a helpful AI assistant",
+            description=self.AGENT_DESCRIPTION,
+            tools=[],
+        )
+
+        # 创建 Team
+        fastapiadmin_team = Team(
+            id=dept_id,
+            user_id=user_id,
+            session_id=session_id,
+            model=OpenAILike(
+                id=settings.OPENAI_MODEL,
+                api_key=settings.OPENAI_API_KEY,
+                base_url=settings.OPENAI_BASE_URL,
+                temperature=self.AGENT_TEMPERATURE,
+            ),
+            members=[fastapiadmin_agent],
+            instructions=self.AGENT_INSTRUCTIONS,
+            expected_output=self.AGENT_EXPECTED_OUTPUT,
+            add_datetime_to_context=True,
+            add_history_to_context=True,
+            markdown=True,
+            num_history_runs=self.NUM_HISTORY_RUNS,
+            input_schema=None,
+            output_schema=None,
+            parse_response=True,
+            read_chat_history=True,
+            db=db,
+        )
+
+        return fastapiadmin_team