gui: auto-reboot after deployment with 60s countdown

Summary screen shows countdown "Restart za Xs..." and reboots automatically.
Buttons: "Restartovat ted" (immediate) and "Zrusit restart" (cancel).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/gui/gui.go

@@ -14,6 +14,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"os/exec"
 	"sync"
 	"time"
 
@@ -324,11 +325,16 @@ func runPhase(runCfg runner.RunConfig, steps []runner.Step) []runner.Result {
 }
 
 // --------------------------------------------------------------------------
-// Phase 3 – Summary
+// Phase 3 – Summary with auto-reboot countdown
 // --------------------------------------------------------------------------
 
+const rebootCountdown = 60 // seconds before automatic reboot
+
 func donePhase(results []runner.Result) {
-	var mw *walk.MainWindow
+	var (
+		mw          *walk.MainWindow
+		countdownLbl *walk.Label
+	)
 
 	ok, errs, skipped := 0, 0, 0
 	rows := make([]Widget, 0, len(results))
@@ -358,6 +364,9 @@ func donePhase(results []runner.Result) {
 
 	summaryText := fmt.Sprintf("OK: %d   CHYBY: %d   PRESKOCENO: %d", ok, errs, skipped)
 
+	// cancelled by "Zrusit restart" button
+	cancelReboot := make(chan struct{})
+
 	if err := (MainWindow{
 		AssignTo: &mw,
 		Title:    "xetup \u2014 hotovo",
@@ -371,7 +380,7 @@ func donePhase(results []runner.Result) {
 			},
 			HSeparator{},
 			ScrollView{
-				MinSize:  Size{Height: 560},
+				MinSize:  Size{Height: 510},
 				Layout:   VBox{MarginsZero: true},
 				Children: rows,
 			},
@@ -381,16 +390,34 @@ func donePhase(results []runner.Result) {
 				Alignment: AlignHCenterVNear,
 				Font:      Font{Bold: true},
 			},
+			Label{
+				AssignTo:  &countdownLbl,
+				Text:      fmt.Sprintf("Restart za %ds...", rebootCountdown),
+				Alignment: AlignHCenterVNear,
+			},
 			Composite{
 				Layout: HBox{MarginsZero: true},
 				Children: []Widget{
 					HSpacer{},
 					PushButton{
-						Text: "  ZAVRIT  ",
+						Text: "  Restartovat ted  ",
 						OnClicked: func() {
+							close(cancelReboot) // signal goroutine to stop ticker
+							reboot()
 							mw.Close()
 						},
 					},
+					PushButton{
+						Text: "  Zrusit restart  ",
+						OnClicked: func() {
+							select {
+							case <-cancelReboot: // already closed
+							default:
+								close(cancelReboot)
+							}
+							countdownLbl.SetText("Restart zrusen.")
+						},
+					},
 					HSpacer{},
 				},
 			},
@@ -399,9 +426,42 @@ func donePhase(results []runner.Result) {
 		return
 	}
 
+	// Countdown goroutine
+	go func() {
+		ticker := time.NewTicker(time.Second)
+		defer ticker.Stop()
+		remaining := rebootCountdown
+		for {
+			select {
+			case <-cancelReboot:
+				return
+			case <-ticker.C:
+				remaining--
+				r := remaining
+				mw.Synchronize(func() {
+					if r > 0 {
+						countdownLbl.SetText(fmt.Sprintf("Restart za %ds...", r))
+					} else {
+						countdownLbl.SetText("Restartuji...")
+					}
+				})
+				if remaining <= 0 {
+					reboot()
+					mw.Synchronize(func() { mw.Close() })
+					return
+				}
+			}
+		}
+	}()
+
 	mw.Run()
 }
 
+// reboot issues an immediate Windows restart.
+func reboot() {
+	exec.Command("shutdown", "/r", "/t", "0").Run() //nolint:errcheck
+}
+
 // --------------------------------------------------------------------------
 // Helpers
 // --------------------------------------------------------------------------