docs(vercel-react-best-practices): 添加 Vercel React 最佳实践规则文档

- 添加 sections 定义文件，包含性能优化各领域分类
- 添加规则模板文件，规范文档结构和标签定义
- 添加异步操作优化规则，包括防止瀑布流、并行化、延迟等待等
- 添加包大小优化规则，包括避免桶式导入、动态导入、预加载等
- 添加服务端性能优化规则，包括 API 路

.agents/skills/vercel-react-best-practices/rules/js-combine-iterations.md

@@ -0,0 +1,32 @@
+---
+title: Combine Multiple Array Iterations
+impact: LOW-MEDIUM
+impactDescription: reduces iterations
+tags: javascript, arrays, loops, performance
+---
+
+## Combine Multiple Array Iterations
+
+Multiple `.filter()` or `.map()` calls iterate the array multiple times. Combine into one loop.
+
+**Incorrect (3 iterations):**
+
+```typescript
+const admins = users.filter(u => u.isAdmin)
+const testers = users.filter(u => u.isTester)
+const inactive = users.filter(u => !u.isActive)
+```
+
+**Correct (1 iteration):**
+
+```typescript
+const admins: User[] = []
+const testers: User[] = []
+const inactive: User[] = []
+
+for (const user of users) {
+  if (user.isAdmin) admins.push(user)
+  if (user.isTester) testers.push(user)
+  if (!user.isActive) inactive.push(user)
+}
+```