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/api/modlists.go

@@ -16,7 +16,7 @@ type createModlistInput struct {
 }
 
 type updateModlistInput struct {
-	Name string          `json:"name" binding:"required"`
+	Name string            `json:"name" binding:"required"`
 	Mods []models.ModEntry `json:"mods"`
 }