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/users/schemas.py

@@ -11,26 +11,19 @@ from pydantic import (
     model_validator,
 )
 
+from schemas.user.context import UserContext
 
-class UserResponse(BaseModel):
-    id: str
-    username: str
-    email: str | None = None
-    avatar_url: str | None = None
-    bio: str | None = None
+
+class UserResponse(UserContext):
+    """当前用户，含 email，无 settings"""
+
+    settings: None = Field(default=None, exclude=True)  # type: ignore[assignment]
 
 
 class UserSearchRequest(BaseModel):
     query: str = Field(min_length=1, max_length=100)
 
 
-class UserSearchResult(BaseModel):
-    id: str
-    username: str
-    avatar_url: str | None = None
-    bio: str | None = None
-
-
 class UserUpdateRequest(BaseModel):
     model_config: ClassVar[ConfigDict] = ConfigDict(extra="forbid")