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

docs/protocols/agent-chat-messages.md

@@ -0,0 +1,69 @@
+# Agent Chat Messages Protocol
+
+> **NOTE**: This document is the single source of truth. All implementations must follow this specification.
+
+## Overview
+
+Chat messages in agent conversations with metadata for tracking and telemetry.
+
+## Version
+
+- **Current**: `1.0`
+- **Status**: Active
+
+---
+
+## Message Metadata
+
+```typescript
+interface AgentChatMessageMetadata {
+  run_id?: string;       // Unique run identifier
+  stage?: string;       // Processing stage (e.g., "intent", "execution")
+  latency_ms?: number;  // Processing latency in milliseconds
+  message_id?: string;  // Message identifier
+  [key: string]: any;   // Additional custom fields allowed
+}
+```
+
+---
+
+## Database Field
+
+| Field | Type | Description |
+|-------|------|-------------|
+| metadata | jsonb | Message metadata including run_id, stage, latency_ms, message_id |
+
+---
+
+## JSON Examples
+
+### Basic Message Metadata
+
+```json
+{
+  "run_id": "run_1773286460762"
+}
+```
+
+### Stage Completion Metadata
+
+```json
+{
+  "run_id": "run_1773286460762",
+  "stage": "intent",
+  "latency_ms": 2610,
+  "message_id": "intent-run_1773286460762"
+}
+```
+
+### Tool Execution Metadata
+
+```json
+{
+  "run_id": "run_1773287162123",
+  "stage": "tool_execution",
+  "latency_ms": 1500,
+  "message_id": "tool_run_abc123",
+  "tool_name": "calendar_create_event"
+}
+```