main: 增强工具调用与消息流程

- 支持 tool.call 和 tool.result 消息类型处理
- 引入 Tool 调度与执行逻辑，支持超时与结果截断
- 增加 ToolRegistry 和 ToolExecutor 管理工具定义与执行
- 更新上下文构建与消息映射逻辑，适配工具闭环处理
- 扩展配置与环境变量，支持 Tool 调用相关选项
- 增强单元测试覆盖工具调用与执行情景
- 更新文档和 OpenAPI，新增工具相关说明与模型定义

docs/ChatSession/chat-session-openapi.yaml

@@ -436,6 +436,8 @@ components:
             - $ref: '#/components/schemas/MessageDeltaPayload'
             - $ref: '#/components/schemas/RunCancelPayload'
             - $ref: '#/components/schemas/RunErrorPayload'
+            - $ref: '#/components/schemas/ToolCallPayload'
+            - $ref: '#/components/schemas/ToolResultPayload'
             - type: object
         reply_to:
           type: string
@@ -544,6 +546,38 @@ components:
         raw_message:
           type: string
           nullable: true
+    ToolCallPayload:
+      type: object
+      properties:
+        run_id:
+          type: string
+        tool_run_id:
+          type: string
+        tool_call_id:
+          type: string
+        name:
+          type: string
+        arguments:
+          type: object
+          additionalProperties: true
+    ToolResultPayload:
+      type: object
+      properties:
+        run_id:
+          type: string
+        parent_run_id:
+          type: string
+        tool_call_id:
+          type: string
+        name:
+          type: string
+        status:
+          type: string
+        error:
+          type: string
+          nullable: true
+        truncated:
+          type: boolean
     PaginationLinks:
       type: object
       properties: