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/schemas/schedule/items.py

@@ -1,8 +1,7 @@
 from __future__ import annotations
 
-import json
 from enum import Enum
-from typing import ClassVar, Literal, Union
+from typing import ClassVar, Literal
 from uuid import UUID
 
 from pydantic import BaseModel, ConfigDict, Field
@@ -46,51 +45,3 @@ class ScheduleItemSourceType(str, Enum):
     MANUAL = "manual"
     IMPORTED = "imported"
     AGENT_GENERATED = "agent_generated"
-
-
-class CalendarInviteContent(BaseModel):
-    model_config: ClassVar[ConfigDict] = ConfigDict(extra="forbid")
-
-    type: Literal["invite"]
-    permission: int = Field(..., description="权限: 1=view, 4=edit, 8=invite")
-    action: Literal["pending"] = "pending"
-
-
-class CalendarUpdateContent(BaseModel):
-    model_config: ClassVar[ConfigDict] = ConfigDict(extra="forbid")
-
-    type: Literal["update"]
-    title: str = Field(..., description="事件标题")
-    action: Literal["updated"] = "updated"
-
-
-class CalendarDeleteContent(BaseModel):
-    model_config: ClassVar[ConfigDict] = ConfigDict(extra="forbid")
-
-    type: Literal["delete"]
-    title: str = Field(..., description="事件标题")
-    action: Literal["deleted"] = "deleted"
-
-
-CalendarContent = Union[
-    CalendarInviteContent,
-    CalendarUpdateContent,
-    CalendarDeleteContent,
-]
-
-
-def parse_calendar_content(content: str | None) -> CalendarContent | None:
-    if not content:
-        return None
-    try:
-        data = json.loads(content)
-        content_type = data.get("type")
-        if content_type == "invite":
-            return CalendarInviteContent(**data)
-        if content_type == "update":
-            return CalendarUpdateContent(**data)
-        if content_type == "delete":
-            return CalendarDeleteContent(**data)
-        raise ValueError(f"Unknown calendar content type: {content_type}")
-    except Exception:
-        return None