fix(ai): 强化拆解切片和测试粒度

apps/web/lib/ai-decompose-dedupe.test.ts

@@ -55,6 +55,7 @@ test('filters dev task drafts already adopted into existing tasks', () => {
       devTaskDrafts: [
         {
           title: '实现拖拽排序',
+          description: '实现范围：支持列表拖拽调整顺序。验收点：拖拽后顺序保持一致。',
           categoryCode: 'frontend_interaction',
           priority: 'P2',
           aiEstimateHours: 0.25,
@@ -123,6 +124,7 @@ test('keeps drafts with same references but different normalized title', () => {
       devTaskDrafts: [
         {
           title: '保存拖拽排序结果',
+          description: '实现范围：保存拖拽后的排序结果。验收点：刷新后顺序不丢失。',
           categoryCode: 'frontend_interaction',
           priority: 'P2',
           aiEstimateHours: 0.5,

apps/web/lib/ai-decompose-target.test.ts

@@ -10,6 +10,7 @@ function makeResult(): AgentDecomposeResult {
     devTaskDrafts: [
       {
         title: '实现登录表单',
+        description: '实现范围：渲染账号密码登录表单。验收点：输入合法信息后可提交。',
         categoryCode: 'frontend_development',
         priority: 'P2',
         aiEstimateHours: 0.5,