perf(backend+frontend): 列表API响应体积优化 3.1MB→145KB (↓95.4%)

- 后端: JPQL构造器投影排除LONGTEXT大字段(uploadedImages/videoReferenceImages)
- 后端: DTO层过滤非分镜图类型的base64内联resultUrl
- 前端: 列表缩略图从video改为img loading=lazy，消除172并发请求
- 前端: download函数增加resultUrl懒加载(详情接口兜底)
- 文档: 新增性能优化报告 docs/performance-optimization-report.md

frontend/src/api/analytics.js

@@ -0,0 +1,20 @@
+import api from './request'
+
+// 获取日活用户趋势数据
+export const getDailyActiveUsersTrend = (year = '2024', granularity = 'monthly') => {
+  return api.get('/analytics/daily-active-users', { 
+    params: { year, granularity } 
+  })
+}
+
+// 获取用户活跃度概览
+export const getUserActivityOverview = () => {
+  return api.get('/analytics/user-activity-overview')
+}
+
+// 获取用户活跃度热力图数据
+export const getUserActivityHeatmap = (year = '2024') => {
+  return api.get('/analytics/user-activity-heatmap', { 
+    params: { year } 
+  })
+}