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/lib/shared/widgets/toast/toast.dart

@@ -48,21 +48,25 @@ class _ToastWidgetState extends State<_ToastWidget>
   late AnimationController _controller;
   late Animation<Offset> _slideAnimation;
   late Animation<double> _fadeAnimation;
+  bool _dismissed = false;
 
   @override
   void initState() {
     super.initState();
     _controller = AnimationController(
-      duration: const Duration(milliseconds: 250),
+      duration: const Duration(milliseconds: 280),
       vsync: this,
     );
 
     _slideAnimation = Tween<Offset>(
-      begin: const Offset(0, -1),
+      begin: const Offset(0, -0.18),
       end: Offset.zero,
-    ).animate(CurvedAnimation(parent: _controller, curve: Curves.easeOut));
+    ).animate(CurvedAnimation(parent: _controller, curve: Curves.easeOutCubic));
 
-    _fadeAnimation = Tween<double>(begin: 0, end: 1).animate(_controller);
+    _fadeAnimation = Tween<double>(
+      begin: 0,
+      end: 1,
+    ).animate(CurvedAnimation(parent: _controller, curve: Curves.easeOut));
 
     _controller.forward();
 
@@ -70,8 +74,13 @@ class _ToastWidgetState extends State<_ToastWidget>
   }
 
   void _dismiss() {
-    if (!mounted) return;
-    _controller.reverse().then((_) => widget.onDismiss());
+    if (!mounted || _dismissed) return;
+    _dismissed = true;
+    _controller.reverse().then((_) {
+      if (mounted) {
+        widget.onDismiss();
+      }
+    });
   }
 
   @override
@@ -85,7 +94,7 @@ class _ToastWidgetState extends State<_ToastWidget>
     final config = ToastTypeConfig.fromType(widget.type);
 
     return Positioned(
-      top: MediaQuery.of(context).padding.top + 16,
+      top: MediaQuery.of(context).padding.top + 12,
       left: 16,
       right: 16,
       child: SlideTransition(
@@ -94,30 +103,74 @@ class _ToastWidgetState extends State<_ToastWidget>
           opacity: _fadeAnimation,
           child: Material(
             color: Colors.transparent,
-            child: Container(
-              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
-              decoration: BoxDecoration(
-                color: config.backgroundColor,
-                borderRadius: BorderRadius.circular(AppRadius.md),
-                boxShadow: [
-                  BoxShadow(
-                    color: Colors.black.withValues(alpha: 0.1),
-                    blurRadius: 8,
-                    offset: const Offset(0, 2),
+            child: SafeArea(
+              bottom: false,
+              child: GestureDetector(
+                onTap: _dismiss,
+                child: Container(
+                  padding: const EdgeInsets.all(12),
+                  decoration: BoxDecoration(
+                    color: config.surfaceColor,
+                    borderRadius: BorderRadius.circular(AppRadius.lg),
+                    border: Border.all(color: config.borderColor),
+                    boxShadow: [
+                      BoxShadow(
+                        color: AppColors.slate900.withValues(alpha: 0.08),
+                        blurRadius: 24,
+                        offset: const Offset(0, 10),
+                      ),
+                    ],
                   ),
-                ],
-              ),
-              child: Row(
-                children: [
-                  Icon(config.icon, size: 20, color: config.iconColor),
-                  const SizedBox(width: 12),
-                  Expanded(
-                    child: Text(
-                      widget.message,
-                      style: TextStyle(fontSize: 14, color: config.textColor),
-                    ),
+                  child: Row(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    children: [
+                      Container(
+                        width: 34,
+                        height: 34,
+                        decoration: BoxDecoration(
+                          color: config.iconColor.withValues(alpha: 0.12),
+                          borderRadius: BorderRadius.circular(AppRadius.full),
+                        ),
+                        child: Icon(
+                          config.icon,
+                          size: 18,
+                          color: config.iconColor,
+                        ),
+                      ),
+                      const SizedBox(width: 10),
+                      Expanded(
+                        child: Column(
+                          crossAxisAlignment: CrossAxisAlignment.start,
+                          children: [
+                            Text(
+                              config.label,
+                              style: TextStyle(
+                                fontSize: 12,
+                                fontWeight: FontWeight.w700,
+                                color: config.textColor,
+                              ),
+                            ),
+                            const SizedBox(height: 2),
+                            Text(
+                              widget.message,
+                              style: TextStyle(
+                                fontSize: 14,
+                                height: 1.35,
+                                color: config.textColor,
+                              ),
+                            ),
+                          ],
+                        ),
+                      ),
+                      const SizedBox(width: 8),
+                      Icon(
+                        Icons.close_rounded,
+                        size: 18,
+                        color: config.textColor.withValues(alpha: 0.72),
+                      ),
+                    ],
                   ),
-                ],
+                ),
               ),
             ),
           ),