add --version flag

ensure version is injected at build time in Taskfile/makefile

cmd/q3rcon-proxy/main.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"runtime/debug"
 	"strconv"
 	"strings"
 	"time"
@@ -15,6 +16,21 @@ import (
 	udpproxy "github.com/onyx-and-iris/q3rcon-proxy"
 )
 
+var version string // Version holds the application version, set at build time using ldflags.
+
+// versionFromBuild retrieves the version information from the build metadata.
+func versionFromBuild() string {
+	if version != "" {
+		return version
+	}
+
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "(unable to read version)"
+	}
+	return strings.Split(info.Main.Version, "-")[0]
+}
+
 // proxyConfig holds the configuration for a single UDP proxy server.
 type proxyConfig struct {
 	proxyHost      string
@@ -24,9 +40,14 @@ type proxyConfig struct {
 }
 
 func main() {
+	cli.VersionPrinter = func(cmd *cli.Command) {
+		fmt.Printf("q3rcon-proxy version: %s\n", cmd.Root().Version)
+	}
+
 	cmd := &cli.Command{
-		Name:  "q3rcon-proxy",
-		Usage: "A Quake 3 RCON proxy server",
+		Name:    "q3rcon-proxy",
+		Usage:   "A Quake 3 RCON proxy server",
+		Version: versionFromBuild(),
 		Flags: []cli.Flag{
 			&cli.StringFlag{
 				Name:    "proxy-host",
@@ -111,7 +132,9 @@ func main() {
 		},
 	}
 
-	log.Fatal(cmd.Run(context.Background(), os.Args))
+	if err := cmd.Run(context.Background(), os.Args); err != nil {
+		log.Fatal(err)
+	}
 }
 
 // launchProxy initialises the UDP proxy server with the given configuration.