fix: parse -o flag correctly to resolve output filename

Fix bug where -o flag value was read as pointer instead of string value,
causing memory addresses to be printed and output path to resolve to ".xlsx".

main.go

@@ -26,10 +26,13 @@ func main() {
 		os.Exit(1)
 	}
 
-	fmt.Println(sep)
-	fmt.Println(enc)
-	fmt.Println(out)
+	if err := run(files, *out, *sep, *enc); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
 
+func run(files []string, out, sep, enc string) error {
 	xlsx := excelize.NewFile()
 	firstSheet := true
 
@@ -49,11 +52,11 @@ func main() {
 		defer f.Close()
 
 		var reader io.Reader = f
-		if *enc == "windows1252" {
+		if enc == "windows1252" {
 			reader = transform.NewReader(f, charmap.Windows1252.NewDecoder())
 		}
 
-		delimiter := detectDelimiter(path, *sep)
+		delimiter := detectDelimiter(path, sep)
 
 		csvReader := csv.NewReader(reader)
 		csvReader.Comma = delimiter
@@ -85,12 +88,11 @@ func main() {
 		fmt.Printf("✓ %s → Reiter \"%s\" (%d Zeilen)\n", path, sheetName, row-1)
 	}
 
-	if err := xlsx.SaveAs(*out); err != nil {
-		fmt.Fprintf(os.Stderr, "Fehler beim Speichern: %v\n", err)
-		os.Exit(1)
+	if err := xlsx.SaveAs(out); err != nil {
+		return fmt.Errorf("Fehler beim Speichern: %w", err)
 	}
-	fmt.Printf("✅ Gespeichert: %s\n", *out)
-
+	fmt.Printf("✅ Gespeichert: %s\n", out)
+	return nil
 }
 
 func detectDelimiter(path, hint string) rune {