fix: add --version flag and correct ldflags module path

- Add --version flag to CLI (closes bd-bxt)
- Fix ldflags module path: csv2excel/internal/version → code.beautifulmachines.dev/jakoubek/csv2excel/internal/version
  so build info (version, commit, date) is actually embedded into the binary
- Add mg.Deps(Build) to Install so it always builds before installing

main.go

@@ -12,14 +12,22 @@ import (
 	"github.com/xuri/excelize/v2"
 	"golang.org/x/text/encoding/charmap"
 	"golang.org/x/text/transform"
+
+	"code.beautifulmachines.dev/jakoubek/csv2excel/internal/version"
 )
 
 func main() {
 	sep := flag.String("sep", "auto", "Trennzeichen: auto, ',', ';', '\\t'")
 	enc := flag.String("enc", "utf8", "Encoding: utf8, windows1252")
 	out := flag.String("o", "output.xlsx", "Ausgabedatei")
+	showVersion := flag.Bool("version", false, "Version anzeigen")
 	flag.Parse()
 
+	if *showVersion {
+		fmt.Printf("csv2excel %s (commit %s, built %s)\n", version.Version, version.Commit, version.BuildDate)
+		os.Exit(0)
+	}
+
 	files := flag.Args()
 	if len(files) == 0 {
 		fmt.Fprintln(os.Stderr, "Verwendung: csv2xlsx [flags] datei1.csv datei2.csv ...")