feat: stamp the build commit, add --version and zap flags, rename module

- module path is now gitea.home.hrajfrisbee.cz/kacerr/gatewayapi-certificates-operator
- internal/version resolves the commit from ldflags or Go build info;
  --version prints it and the first log line carries it
- --metrics-bind-address is passed to the manager instead of being dropped
- Dockerfile takes GIT_COMMIT, honours TARGETARCH, labels the image revision

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

main.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"os"
+	goruntime "runtime"
 
 	cmv1 "github.com/cert-manager/cert-manager/pkg/apis/certmanager/v1"
 	gozap "go.uber.org/zap"
@@ -12,9 +14,11 @@ import (
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	"sigs.k8s.io/controller-runtime/pkg/log/zap"
+	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 	gwapiv1 "sigs.k8s.io/gateway-api/apis/v1"
 
-	"github.com/example/gateway-cert-operator/internal/controller"
+	"gitea.home.hrajfrisbee.cz/kacerr/gatewayapi-certificates-operator/internal/controller"
+	"gitea.home.hrajfrisbee.cz/kacerr/gatewayapi-certificates-operator/internal/version"
 )
 
 var scheme = runtime.NewScheme()
@@ -28,21 +32,27 @@ func init() {
 func main() {
 	var metricsAddr string
 	var probeAddr string
+	var showVersion bool
 
 	flag.StringVar(&metricsAddr, "metrics-bind-address", ":8080", "The address the metrics endpoint binds to.")
 	flag.StringVar(&probeAddr, "health-probe-bind-address", ":8081", "The address the probe endpoint binds to.")
+	flag.BoolVar(&showVersion, "version", false, "Print the commit this binary was built from and exit.")
+	opts := zap.Options{Development: true, ZapOpts: []gozap.Option{gozap.AddCaller()}}
+	opts.BindFlags(flag.CommandLine)
 	flag.Parse()
 
-	ctrl.SetLogger(zap.New(
-		zap.UseDevMode(true),
-		func(o *zap.Options) {
-			o.ZapOpts = append(o.ZapOpts, gozap.AddCaller())
-		},
-	))
+	if showVersion {
+		fmt.Println(version.Resolve())
+		return
+	}
+
+	ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
 	log := ctrl.Log.WithName("setup")
+	log.Info("starting gateway-cert-operator", "commit", version.Resolve(), "goVersion", goruntime.Version())
 
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
 		Scheme:                 scheme,
+		Metrics:                metricsserver.Options{BindAddress: metricsAddr},
 		HealthProbeBindAddress: probeAddr,
 	})
 	if err != nil {