[API] Missing NestJS lifecycle cleanup — intervals, recursive timeouts, stale WS refs

[Flegma]

Summary

Several services create intervals, timeouts, and track connections but never clean them up on module shutdown.

Findings

• RedisManagerService — setInterval health checks stored in map but no onApplicationShutdown hook to clear them.
• MatchAssistantService — setTimeout calls assignServer recursively with no max depth or cleanup reference.
• SocketsGateway — has handleConnection but no handleDisconnect, leaving stale client references.

Impact

Memory usage grows over time. After extended uptime, services may experience degraded performance or OOM.

Suggested Fix

• Add OnApplicationShutdown or OnModuleDestroy lifecycle hooks to clear intervals/timeouts.
• Add handleDisconnect to SocketsGateway.
• Cap recursive setTimeout depth and store reference for cleanup.

---

Related Issues (Memory Leak Pattern)

• [API] Missing NestJS lifecycle cleanup — intervals, recursive timeouts, stale WS refs #375 — [API] Missing NestJS lifecycle cleanup
• [Web] GraphQL subscription leaks — NotificationStore, ApplicationSettings, Matchmaking, MatchLobby #385 — [Web] GraphQL subscription leaks
• [Web] Socket listeners & component event handlers never cleaned up #386 — [Web] Socket listeners never cleaned up
• [Game Server] Resource disposal — HttpClient, WebSocket, Timer, pending messages accumulation #398 — [Game Server] Resource disposal issues
• [Connector] Network monitoring process leak & throttle instance accumulation #407 — [Connector] Network process leak & throttle accumulation