feat(worker): add device registration_id cleanup worker

Add DeviceCleanupWorker to periodically clean up stale device tokens that haven't
been used within the retention period. This prevents accumulation of invalid
registration_ids and maintains data hygiene.

- New DeviceCleanupConfig with enabled, retention_days (3), and interval_minutes (360)
- New repository methods DeleteStaleDevices and DeleteOldestActiveDevice
- Updated RegisterDevice to evict oldest active device when reaching limit
- Reduced MaxDevicesPerUser from 10 to 3 per user
- Worker integrated into app startup/shutdown lifecycle

cmd/server/app.go

@@ -24,6 +24,7 @@ type App struct {
 	PushService        service.PushService
 	HotRankWorker      *service.HotRankWorker
 	FileCleanupWorker  *service.FileCleanupWorker
+	DeviceCleanupWorker *service.DeviceCleanupWorker
 	GRPCServer         *runner.Server
 	Server             *http.Server
 	Publisher          ws.MessagePublisher
@@ -40,6 +41,7 @@ func NewApp(
 	pushService service.PushService,
 	hotRankWorker *service.HotRankWorker,
 	fileCleanupWorker *service.FileCleanupWorker,
+	deviceCleanupWorker *service.DeviceCleanupWorker,
 	grpcServer *runner.Server,
 	publisher ws.MessagePublisher,
 	taskDispatcher runner.TaskDispatcher,
@@ -53,6 +55,7 @@ func NewApp(
 		PushService:        pushService,
 		HotRankWorker:      hotRankWorker,
 		FileCleanupWorker:  fileCleanupWorker,
+		DeviceCleanupWorker: deviceCleanupWorker,
 		GRPCServer:         grpcServer,
 		Publisher:          publisher,
 		TaskDispatcher:     taskDispatcher,
@@ -84,6 +87,11 @@ func (a *App) Start(ctx context.Context) error {
 		a.FileCleanupWorker.Start(ctx)
 	}
 
+	// 2.1.2 设备 registration_id 清理（清理不活跃设备 token）
+	if a.DeviceCleanupWorker != nil {
+		a.DeviceCleanupWorker.Start(ctx)
+	}
+
 	// 2.2 启动 PushWorker（Redis Stream 异步推送）
 	if a.PushWorker != nil {
 		a.PushWorker.Start(ctx)
@@ -169,6 +177,11 @@ func (a *App) Stop(ctx context.Context) error {
 		a.FileCleanupWorker.Stop()
 	}
 
+	if a.DeviceCleanupWorker != nil {
+		a.Logger.Info("Stopping device cleanup worker")
+		a.DeviceCleanupWorker.Stop()
+	}
+
 	// 5.1 停止 PushWorker
 	if a.PushWorker != nil {
 		a.Logger.Info("Stopping push worker (stream)")