docs: update agent architecture and fix mermaid syntax in README

README.md

@@ -116,10 +116,10 @@ graph BT
     end
 
     subgraph "Layer 1: 静态红线层 (Redline Layer)"
-        L1_1[禁止 API 幻觉 (Context7 强制)]
-        L1_2[禁止 XSS / 浮点金额计算]
-        L1_3[禁止直接修改非代码文件]
-        L1_4[只读模式 (@planning)]
+        L1_1["禁止 API 幻觉 (Context7 强制)"]
+        L1_2["禁止 XSS / 浮点金额计算"]
+        L1_3["禁止直接修改非代码文件"]
+        L1_4["只读模式 (@planning)"]
     end
 
     L1_1 --> L2_1
@@ -163,6 +163,8 @@ graph BT
     ├── business/            # 💼 业务域
     │   ├── order-management/
     │   └── product-management/
+    ├── design/              # 🎨 设计规范
+    │   └── visual-standards/
     ├── tech-stack/          # 🛠️ 技术栈
     │   └── umijs-procomponents/
     └── engineering/         # 🛡️ 通用工程