feat: 完成极简 LangGraph 架构迁移，添加 Baosi API 支持

主要变更：
- 迁移到极简 LangGraph 标准架构（START → init_state → 记忆 → Agent ⇄ Tools → finalize → END）
- 添加 Baosi API 支持，配置 ops4.7 模型
- 保留本地模型作为默认首选，Baosi 作为备选
- 新架构使用 LangGraph 原生 ToolNode 和 bind_tools
- 移除旧的混合路由、JSON 解析等复杂逻辑
- 把旧代码移到 deprecated/ 目录
- 添加新的 Agent 节点和 Tools 模块
- 添加测试脚本验证新架构
- 所有测试通过 ✓

backend/app/main_graph/state.py

@@ -1,148 +1,37 @@
 """
-主图状态定义 - React 模式增强版
-Main Graph State Definition - React Mode Enhanced
+极简 Agent 状态定义 - 只保留真正需要的字段
 
-字段分类说明：
-- 持久化字段：跨轮次保留，不重置
-- 临时字段：每轮对话开始时重置
+保留的核心字段：
+- messages: 对话历史（LangGraph 必需）
+- user_id: 用户标识
+- 记忆相关：turns_since_last_summary, memory_context
+- 安全限制：current_step, max_steps
+- 统计：llm_calls, last_token_usage, last_elapsed_time
 """
 
-from enum import Enum, auto
-from typing import Optional, Dict, Any, Annotated, Sequence, TypedDict, List
+from typing import Annotated, Sequence, Optional, Dict, Any
 from dataclasses import dataclass, field
 from langgraph.graph import add_messages
 from langchain_core.messages import BaseMessage
 
 
-# ========== 枚举类型 ==========
-class CurrentAction(Enum):
-    """主图当前操作类型"""
-    NONE = auto()
-    GENERAL_CHAT = auto()
-    NEWS_ANALYSIS = auto()
-    DICTIONARY = auto()
-    CONTACT = auto()
-
-
-class ErrorSeverity(Enum):
-    """错误严重程度"""
-    INFO = auto()     # 信息级别，继续执行
-    WARNING = auto()  # 警告级别，可以重试
-    ERROR = auto()    # 错误级别，需要处理
-    FATAL = auto()    # 致命错误，终止执行
-
-
 @dataclass
-class ErrorRecord:
-    """错误记录"""
-    error_type: str
-    error_message: str
-    severity: ErrorSeverity = ErrorSeverity.ERROR
-    source: str = ""  # 来源：哪个节点/子图/工具
-    timestamp: str = ""
-    retry_count: int = 0  # 已重试次数
-    max_retries: int = 3  # 最大重试次数
-    context: Dict[str, Any] = field(default_factory=dict)  # 错误上下文
-
-
-@dataclass
-class ReactReasoningState:
-    """React 推理状态"""
-    last_reasoning: Optional[Dict[str, Any]] = None
-    reasoning_result: Optional[Any] = None  # 实际类型是 ReasoningResult
-
-
-@dataclass
-class HybridRouterState:
-    """混合路由状态"""
-    decision: Optional[Any] = None  # 实际类型是 HybridRouterResult
-    start_time: Optional[str] = None
-
-
-@dataclass
-class FastPathState:
-    """快速路径状态"""
-    chitchat_success: bool = False
-    rag_success: bool = False
-    tool_success: bool = False
-    failed: bool = False
-    fail_reason: str = ""
-
-
-@dataclass
-class MainGraphState:
-    """
-    主图状态定义
-    
-    字段分类：
-    - 持久化字段：跨轮次保留，不重置
-    - 临时字段：每轮对话开始时重置
-    """
-    
-    # ==================================================
-    # 持久化字段（每轮保留）
-    # ==================================================
+class AgentState:
+    """Agent 状态"""
     
+    # ========== 核心持久化字段（必需） ==========
     messages: Annotated[Sequence[BaseMessage], add_messages] = field(default_factory=list)
-    turns_since_last_summary: int = 0  # 距离上次总结的轮数
     user_id: str = ""
     
-    # ==================================================
-    # 临时字段（每轮重置）
-    # ==================================================
+    # ========== 安全限制字段（防止无限循环） ==========
+    max_steps: int = 10
+    current_step: int = 0
     
-    # 主图控制字段
-    user_query: str = ""
-    current_action: CurrentAction = CurrentAction.NONE
-    current_model: str = ""  # 本次请求使用的模型
-    intent_confidence: float = 0.0
+    # ========== 记忆相关字段（保留） ==========
+    turns_since_last_summary: int = 0
+    memory_context: str = ""
     
-    # React 推理专用字段
-    reasoning_step: int = 0
-    max_steps: int = 10  # 避免过长循环
-    last_action: str = ""
-    reasoning_history: List[Dict[str, Any]] = field(default_factory=list)
-    
-    # RAG 相关字段
-    rag_context: str = ""
-    rag_retrieved: bool = False
-    rag_docs: List[Dict[str, Any]] = field(default_factory=list)
-    rag_confidence: float = 0.0  # RAG 检索置信度 (0.0-1.0)
-    rag_attempts: int = 0  # RAG 检索次数统计
-    
-    # 联网搜索相关字段
-    web_search_results: List[str] = field(default_factory=list)
-    
-    # 错误处理字段
-    errors: List[ErrorRecord] = field(default_factory=list)
-    current_error: Optional[ErrorRecord] = None
-    retry_action: Optional[str] = None
-    error_message: str = ""
-    
-    # 子图结果字段
-    news_result: Optional[Dict[str, Any]] = None
-    dictionary_result: Optional[Dict[str, Any]] = None
-    contact_result: Optional[Dict[str, Any]] = None
-    
-    # 执行状态
-    current_phase: str = "init"
-    final_result: str = ""
-    success: bool = False
-    
-    # 元数据
-    start_time: Optional[str] = None
-    end_time: Optional[str] = None
-    
-    # 结构化状态
-    react_reasoning: ReactReasoningState = field(default_factory=ReactReasoningState)
-    hybrid_router: HybridRouterState = field(default_factory=HybridRouterState)
-    fast_path: FastPathState = field(default_factory=FastPathState)
-    
-    # 统计字段（用于反馈）
+    # ========== 统计字段（保留） ==========
     llm_calls: int = 0
     last_token_usage: Dict[str, Any] = field(default_factory=dict)
     last_elapsed_time: float = 0.0
-    memory_context: str = ""  # 记忆检索结果
-    
-    # 向后兼容（保留但不推荐使用）
-    debug_info: Dict[str, Any] = field(default_factory=dict)