feat(ov): windowed dedup visit counting with retention cleanup

Task 8 (P2): POST /public/albums/{token}/visits with visit_sessions
window dedup (VISIT_WINDOW_MINUTES), requestId idempotent replay
(echoes stored outcome; expired beyond VISIT_REQUEST_TTL_MINUTES
rejected), album_stats viewCount/statVersion authority + outbox_stat_events
views snapshots, WS stats.updated broadcast, visitorId+IP fixed-window
rate limit (VISIT_WINDOW_REQUESTS), and ov CleanupModule scheduler
(setInterval, CLEANUP_INTERVAL_MINUTES) deleting like_batches /
visit_requests / visit_sessions past their windows — totals never
touched. Contract prose aligned to replay semantics; constants
VISIT_WINDOW_REQUESTS / CLEANUP_INTERVAL_MINUTES added.

Co-Authored-By: Claude Code <noreply@anthropic.com>

services/api/src/cleanup/cleanup.module.ts

@@ -0,0 +1,16 @@
+// services/api/src/cleanup/ —— ov 互动流水清理模块（P2 Task 8）。仅 ov 入口
+// 装配（app-ov.module 显式挑选；cn 入口不感知——cn 侧无互动流水表）。
+// CleanupService 同时导出：调度（setInterval，见 cleanup.service.ts 头注）
+// 与 runCleanupOnce（e2e 直调断言）。语义边界：仅清 like_batches /
+// visit_requests / visit_sessions 超窗口行，累计总数（album_stats、
+// photos_ov.likeTotal）永不触碰。
+import { Module } from '@nestjs/common';
+import { OvPrismaModule } from '../prisma-ov/ov-prisma.module';
+import { CleanupService } from './cleanup.service';
+
+@Module({
+  imports: [OvPrismaModule],
+  providers: [CleanupService],
+  exports: [CleanupService],
+})
+export class CleanupModule {}