♻️ 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/__init__.py

@@ -27,23 +27,19 @@ from .llm import (
     LLMException,
     LLMGenerationConfig,
     LLMMessage,
-    analyze,
-    analyze_multimodal,
     chat,
     clear_model_cache,
     code,
     create_multimodal_message,
     embed,
     generate,
+    generate_structured,
     get_cache_stats,
     get_model_instance,
     list_available_models,
     list_embedding_models,
-    pipeline_chat,
     search,
-    search_multimodal,
     set_global_default_model_name,
-    tool_registry,
 )
 from .log import logger
 from .plugin_init import PluginInit, PluginInitManager
@@ -60,8 +56,6 @@ __all__ = [
     "Model",
     "PluginInit",
     "PluginInitManager",
-    "analyze",
-    "analyze_multimodal",
     "chat",
     "clear_model_cache",
     "code",
@@ -69,16 +63,14 @@ __all__ = [
     "disconnect",
     "embed",
     "generate",
+    "generate_structured",
     "get_cache_stats",
     "get_model_instance",
     "list_available_models",
     "list_embedding_models",
     "logger",
-    "pipeline_chat",
     "scheduler_manager",
     "search",
-    "search_multimodal",
     "set_global_default_model_name",
-    "tool_registry",
     "with_db_timeout",
 ]