feat: Add version command

Author: chebread

.goreleaser.yml

@@ -1,6 +1,8 @@
 builds:
   - env:
       - CGO_ENABLED=0
+    ldflags:
+      - -X 'main.ProgramVersion={{.Version}}'
     goos:
       - linux
       - windows

data.go

@@ -2,6 +2,8 @@ package main
 
 import "time"
 
+var ProgramVersion = "development" // It will be replaced with a git tag.
+
 // 지원 통화
 var currencyList = [...]string{
 	"KRW",

go.mod

@@ -2,8 +2,9 @@ module cvtr
 
 go 1.24.4
 
+require github.com/fatih/color v1.18.0
+
 require (
-	github.com/fatih/color v1.18.0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	golang.org/x/sys v0.25.0 // indirect

main.go

@@ -199,8 +199,10 @@ func main() {
 				boldCyan("%s\n", comma(result))
 
 			}
-		case "help":
+		case "help", "-h", "--help":
 			help()
+		case "version", "-V", "-v", "--version":
+			fmt.Printf("cvtr %s\n", ProgramVersion)
 		default:
 			boldRed("error: %s is an invalid command\n", os.Args[1])
 		}