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/server_process.go

@@ -148,8 +148,8 @@ func (pm *ProcessManager) Start() error {
 	pm.mu.Unlock()
 	pm.state.Store(int32(procRunning))
 
-	go pm.streamer.Stream("server", stdout, "")
-	go pm.streamer.Stream("server", stderr, "")
+	go pm.streamer.Stream(ctx, "server", stdout, "")
+	go pm.streamer.Stream(ctx, "server", stderr, "")
 
 	go func() {
 		cmd.Wait()