feat: AG-UI 协议对齐与路由导航功能

- 前端: 添加 SSE 流式支持、stateSnapshot 事件、路由导航工具
- 前端: 实现工具调用审批流程，支持 pending 状态展示
- 后端: Agent 状态管理与会话持久化相关重构
- 文档: 新增 agent-agui-full-alignance 设计文档
- 测试: 补充相关单元测试和集成测试

backend/src/v1/agent/schemas.py

@@ -1,18 +1,12 @@
 from __future__ import annotations
 
-from pydantic import BaseModel, Field
-
-
-class RunRequest(BaseModel):
-    session_id: str | None = Field(default=None, min_length=1, max_length=100)
-    prompt: str = Field(min_length=1, max_length=5000)
-
-
-class ResumeRequest(BaseModel):
-    tool_call_id: str = Field(min_length=1, max_length=200)
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class TaskAcceptedResponse(BaseModel):
-    task_id: str
-    session_id: str
+    model_config = ConfigDict(populate_by_name=True, serialize_by_alias=True)
+
+    task_id: str = Field(alias="taskId")
+    thread_id: str = Field(alias="threadId")
+    run_id: str = Field(alias="runId")
     created: bool