fix(backend): fix memory leaks and resource issues in logs system

- Fix Subscribe overwriting channel without closing old one (goroutine leak)
- Add context.Context to Stream() for cancellation support
- Add WebSocket read pump to detect dead clients (StreamLogs, StreamSteamCMDLogs, StreamRPTLogs)
- Use defer f.Close() pattern in StreamRPTLogs file handling
- Fix findLatestRPT nil dereference on failed os.Stat
- Optimize findLatestRPT to collect stat results before sorting
- Apply gofmt formatting to modlists.go, settings.go

backend/internal/services/steamcmd.go

@@ -117,8 +117,8 @@ func (s *SteamCmdManager) run(label string, args []string) error {
 
 	s.cancel = cancel
 
-	go s.streamer.Stream("steamcmd", stdout, "")
-	go s.streamer.Stream("steamcmd", stderr, "")
+	go s.streamer.Stream(ctx, "steamcmd", stdout, "")
+	go s.streamer.Stream(ctx, "steamcmd", stderr, "")
 
 	go func() {
 		err := cmd.Wait()