feat: 添加视觉设计语言系统并重构认证页面UI

- 新增 visual_design_language.md 设计规范文档
- 新增 auth 设计 tokens (authBackground, authCard, authInput, feedback 系列等)
- 重构登录/注册/验证码/重置密码页面为新设计系统
- 新增 AuthHeroHeader, AuthSurfaceCard, AuthSection, AuthField, PasswordField 组件
- 重构 AppBanner 和 Toast 支持多类型配置 (info/success/warning/error)
- 后端 AgentScope: 重整 schemas/prompts/tools 作用域, 新增协议文档
- 更新 AGENTS.md 集成视觉设计语言约束

backend/src/v1/agent/router.py

@@ -1,39 +1,38 @@
 from __future__ import annotations
 
-from collections.abc import AsyncIterator
 import asyncio
-from datetime import date
 import os
 import re
 import tempfile
 import time
+from collections.abc import AsyncIterator
+from datetime import date
 from typing import Annotated, Union
 
 from ag_ui.core import RunAgentInput
+from core.agentscope.events import to_sse_event
+from core.auth.jwt_verifier import JwtVerifier, TokenValidationError
+from core.auth.models import CurrentUser
+from core.config.settings import config
+from core.logging import get_logger
 from fastapi import (
     APIRouter,
     Depends,
     File,
     Form,
     Header,
+    HTTPException,
     Query,
     Request,
-    status,
     UploadFile,
+    status,
 )
-from fastapi import HTTPException
 from fastapi.responses import JSONResponse, StreamingResponse
-
-from core.agentscope.events import to_sse_event
-from core.agentscope.schemas.agui_input import (
+from schemas.agent.agui_input import (
     extract_latest_tool_result,
     parse_run_input,
     validate_run_request_messages_contract,
 )
-from core.auth.jwt_verifier import JwtVerifier, TokenValidationError
-from core.auth.models import CurrentUser
-from core.config.settings import config
-from core.logging import get_logger
 from services.base.redis import get_or_init_redis_client
 from v1.agent.dependencies import get_agent_service
 from v1.agent.schemas import (