♻️ refactor!: 重构LLM服务架构并统一Pydantic兼容性处理 (#2002)

* ♻️ refactor(pydantic): 提取 Pydantic 兼容函数到独立模块

* ♻️ refactor!(llm): 重构LLM服务，引入现代化工具和执行器架构

🏗️ **架构变更**
- 引入ToolProvider/ToolExecutable协议，取代ToolRegistry
- 新增LLMToolExecutor，分离工具调用逻辑
- 新增BaseMemory抽象，解耦会话状态管理

🔄 **API重构**
- 移除：analyze, analyze_multimodal, pipeline_chat
- 新增：generate_structured, run_with_tools
- 重构：chat, search, code变为无状态调用

🛠️ **工具系统**
- 新增@function_tool装饰器
- 统一工具定义到ToolExecutable协议
- 移除MCP工具系统和mcp_tools.json

---------

Co-authored-by: webjoin111 <455457521@qq.com>

zhenxun/services/llm/memory.py

@@ -0,0 +1,55 @@
+from abc import ABC, abstractmethod
+from collections import defaultdict
+from typing import Any
+
+from .types import LLMMessage
+
+
+class BaseMemory(ABC):
+    """
+    记忆系统的抽象基类。
+    定义了任何记忆后端都必须实现的接口。
+    """
+
+    @abstractmethod
+    async def get_history(self, session_id: str) -> list[LLMMessage]:
+        """根据会话ID获取历史记录。"""
+        raise NotImplementedError
+
+    @abstractmethod
+    async def add_message(self, session_id: str, message: LLMMessage) -> None:
+        """向指定会话添加一条消息。"""
+        raise NotImplementedError
+
+    @abstractmethod
+    async def add_messages(self, session_id: str, messages: list[LLMMessage]) -> None:
+        """向指定会话添加多条消息。"""
+        raise NotImplementedError
+
+    @abstractmethod
+    async def clear_history(self, session_id: str) -> None:
+        """清空指定会话的历史记录。"""
+        raise NotImplementedError
+
+
+class InMemoryMemory(BaseMemory):
+    """
+    一个简单的、默认的内存记忆后端。
+    将历史记录存储在进程内存中的字典里。
+    """
+
+    def __init__(self, **kwargs: Any):
+        self._history: dict[str, list[LLMMessage]] = defaultdict(list)
+
+    async def get_history(self, session_id: str) -> list[LLMMessage]:
+        return self._history.get(session_id, []).copy()
+
+    async def add_message(self, session_id: str, message: LLMMessage) -> None:
+        self._history[session_id].append(message)
+
+    async def add_messages(self, session_id: str, messages: list[LLMMessage]) -> None:
+        self._history[session_id].extend(messages)
+
+    async def clear_history(self, session_id: str) -> None:
+        if session_id in self._history:
+            del self._history[session_id]