feat: port flag

internal/app/file.go

@@ -2,14 +2,14 @@ package app
 
 import (
 	"errors"
-	"os"
+	"flag"
 	"strings"
 )
 
 func GetFilePath() (string, error) {
 	fp := ""
 
-	for _, v := range os.Args[1:] {
+	for _, v := range flag.Args() {
 		if !strings.HasPrefix(v, "-") {
 			fp = v
 			return fp, nil