fix: resolve all golangci-lint errors

- Add error checks for w.Write, json.Encode, os.MkdirAll, os.WriteFile, file.Seek
- Fix gosimple S1000: use for range instead of for { select {} }
- Fix ineffectual assignments in adaptive_io.go
- Add nolint directives for unused code intended for future use
- Fix SA1029: use custom contextKey type instead of string
- Fix SA9003: remove empty branch in client_network_handler.go
- All linting checks now pass

cmd/monitor/monitor.go

@@ -474,10 +474,11 @@ func countHmacErrors() (int, error) {
 	}
 
 	// Limit to last 1MB for large log files
-	var startPos int64 = 0
 	if stat.Size() > 1024*1024 {
-		startPos = stat.Size() - 1024*1024
-		file.Seek(startPos, io.SeekStart)
+		startPos := stat.Size() - 1024*1024
+		if _, err := file.Seek(startPos, io.SeekStart); err != nil {
+			return 0, err
+		}
 	}
 
 	scanner := bufio.NewScanner(file)