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/log_streamer.go

@@ -2,6 +2,7 @@ package services
 
 import (
 	"bufio"
+	"context"
 	"io"
 	"log"
 	"sync"
@@ -26,6 +27,10 @@ func (ls *LogStreamer) Subscribe(serverID, clientID string) chan string {
 		ls.subs[serverID] = make(map[string]chan string)
 	}
 
+	if old, ok := ls.subs[serverID][clientID]; ok {
+		close(old)
+	}
+
 	ch := make(chan string, 256)
 	ls.subs[serverID][clientID] = ch
 	return ch
@@ -46,14 +51,23 @@ func (ls *LogStreamer) Unsubscribe(serverID, clientID string) {
 	}
 }
 
-func (ls *LogStreamer) Stream(serverID string, reader io.Reader, closeMsg string) {
+func (ls *LogStreamer) Stream(ctx context.Context, serverID string, reader io.Reader, closeMsg string) {
 	scanner := bufio.NewScanner(reader)
 	for scanner.Scan() {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+		}
 		line := scanner.Text()
 		ls.broadcast(serverID, line)
 	}
 	if err := scanner.Err(); err != nil {
-		log.Printf("log stream error for server %s: %v", serverID, err)
+		select {
+		case <-ctx.Done():
+		default:
+			log.Printf("log stream error for server %s: %v", serverID, err)
+		}
 	}
 	if closeMsg != "" {
 		ls.broadcast(serverID, closeMsg)