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

apps/AGENTS.md

@@ -6,6 +6,7 @@ This document defines **hard constraints** for Flutter mobile development. Treat
 
 - This file applies to all changes under `apps/**`.
 - It extends root routing rules in `AGENTS.md` and workspace global runtime rules.
+- It also incorporates the visual design language from `apps/rules/visual_design_language.md` as a binding constraint.
 - If rules conflict, apply the stricter requirement.
 - Keep Flutter-specific constraints in this file; avoid duplicating them in root `AGENTS.md`.
 
@@ -15,15 +16,17 @@ This document defines **hard constraints** for Flutter mobile development. Treat
   - Colors: `AppColors.*`
   - Spacing: `AppSpacing.*`
   - Radius: `AppRadius.*`
-- **MUST NOT** hardcode any visual values, including (but not limited to): colors, font sizes, spacing, padding/margins, widths/heights, radii, shadows, opacity, or “magic numbers”.
-  - Examples that are **NOT allowed**: `Color(0xFF...)`, `SizedBox(height: 12)`, `EdgeInsets.all(16)`, `Radius.circular(8)`.
+- **MUST NOT** hardcode any visual values.
+- Design tokens are the single source of truth for all visual values. Any missing visual semantics should be added to tokens, not approximated locally.
+- This ensures consistency with the visual design language defined in `apps/rules/visual_design_language.md`.
 
-## 2) Component Reuse (MUST)
+## 2) Component Architecture (MUST)
 
-- **MUST** prefer existing components and established page patterns over creating new UI components.
-- **MUST** use:
-  - Buttons: `AppButton` from `apps/lib/shared/widgets/app_button.dart`
-- **MUST NOT** introduce parallel UI systems (custom buttons, custom loading systems, custom input wrappers) unless explicitly required and approved.
+- **SHOULD** extract repeated UI patterns into reusable components.
+- **SHOULD** prefer existing shared components before creating new ones.
+- **SHOULD** place reusable components in `apps/lib/shared/widgets/` following existing naming conventions.
+- **MUST NOT** introduce parallel UI systems (e.g., custom button styles, custom loading indicators) that duplicate existing shared components.
+- When creating new UI components, ensure they follow the design tokens and visual design language.
 
 ## 3) Layout Mapping & Alignment (MUST)
 
@@ -73,3 +76,33 @@ Agent chat functionality **MUST** follow the AG-UI protocol. **Use the `ag-ui` s
 - **MUST NOT** return non-streaming responses for agent chat.
 - **MUST NOT** omit required lifecycle events.
 - **MUST NOT** use non-AG-UI event formats (except where the spec explicitly allows).
+
+## 8) Visual Design Language (MUST)
+
+All UI/UX work **MUST** follow the visual design language defined in `apps/rules/visual_design_language.md`.
+
+- **MUST** ensure screens feel like a premium personal assistant product, not a wireframe, admin console, or document page.
+- **MUST** apply the surface-based design system (background, primary, secondary, interactive surfaces).
+- **MUST** follow the motion and interaction feel guidelines (soft, responsive, premium).
+- **MUST** achieve visual hierarchy through spacing, surface grouping, radius, depth, density, contrast, scale, and motion—not color alone.
+- **MUST** follow the screen-level decision rules:
+  1. What is the primary focus?
+  2. What is the surface hierarchy?
+  3. What needs strongest emphasis?
+  4. What should be grouped?
+  5. What should be lightweight/secondary?
+  6. Where should motion reinforce understanding?
+  7. How can the result feel more like a premium assistant app and less like a document page?
+- **MUST NOT** create UIs that match the anti-patterns listed in the visual design language document:
+  - plain document page, white slab with blue buttons, spreadsheet-like admin panel
+  - low-fidelity wireframe, default Flutter demo app, generic template marketplace screen
+  - full-screen flat white blocks, arbitrary shadow usage, inconsistent card treatments
+  - raw container stacking without surface semantics
+
+Before finalizing any UI, mentally verify:
+- Does this feel like a product, not a page?
+- Is there clear hierarchy?
+- Do surfaces feel intentional?
+- Does the screen feel calm and premium?
+- Is the assistant identity visually present?
+- Would this look plausible in a polished shipping app?