refactor: extract newProgressBar helper with named constants

Extract duplicated progress bar creation into (v *Vaultik) newProgressBar()
helper method. Define progressBarWidth and progressBarThrottle constants to
replace bare magic numbers (40, 100ms) that appeared in both the restore
and verify progress bar blocks.

internal/vaultik/restore.go

@@ -22,6 +22,13 @@ import (
 	"golang.org/x/term"
 )
 
+const (
+	// progressBarWidth is the character width of the progress bar display.
+	progressBarWidth = 40
+	// progressBarThrottle is the minimum interval between progress bar redraws.
+	progressBarThrottle = 100 * time.Millisecond
+)
+
 // RestoreOptions contains options for the restore operation
 type RestoreOptions struct {
 	SnapshotID string
@@ -122,22 +129,7 @@ func (v *Vaultik) Restore(opts *RestoreOptions) error {
 	}
 
 	// Create progress bar if output is a terminal
-	var bar *progressbar.ProgressBar
+	bar := v.newProgressBar("Restoring", totalBytesExpected)
-	if v.isTerminal() {
-		bar = progressbar.NewOptions64(
-			totalBytesExpected,
-			progressbar.OptionSetDescription("Restoring"),
-			progressbar.OptionSetWriter(v.Stderr),
-			progressbar.OptionShowBytes(true),
-			progressbar.OptionShowCount(),
-			progressbar.OptionSetWidth(40),
-			progressbar.OptionThrottle(100*time.Millisecond),
-			progressbar.OptionOnCompletion(func() {
-				v.printfStderr("\n")
-			}),
-			progressbar.OptionSetRenderBlankState(true),
-		)
-	}
 
 	for i, file := range files {
 		if v.ctx.Err() != nil {
@@ -572,22 +564,7 @@ func (v *Vaultik) verifyRestoredFiles(
 	)
 
 	// Create progress bar if output is a terminal
-	var bar *progressbar.ProgressBar
+	bar := v.newProgressBar("Verifying", totalBytes)
-	if v.isTerminal() {
-		bar = progressbar.NewOptions64(
-			totalBytes,
-			progressbar.OptionSetDescription("Verifying"),
-			progressbar.OptionSetWriter(v.Stderr),
-			progressbar.OptionShowBytes(true),
-			progressbar.OptionShowCount(),
-			progressbar.OptionSetWidth(40),
-			progressbar.OptionThrottle(100*time.Millisecond),
-			progressbar.OptionOnCompletion(func() {
-				v.printfStderr("\n")
-			}),
-			progressbar.OptionSetRenderBlankState(true),
-		)
-	}
 
 	// Verify each file
 	for _, file := range regularFiles {
@@ -681,6 +658,27 @@ func (v *Vaultik) verifyFile(
 	return bytesVerified, nil
 }
 
+// newProgressBar creates a terminal-aware progress bar with standard options.
+// It returns nil if stdout is not a terminal.
+func (v *Vaultik) newProgressBar(description string, total int64) *progressbar.ProgressBar {
+	if !v.isTerminal() {
+		return nil
+	}
+	return progressbar.NewOptions64(
+		total,
+		progressbar.OptionSetDescription(description),
+		progressbar.OptionSetWriter(v.Stderr),
+		progressbar.OptionShowBytes(true),
+		progressbar.OptionShowCount(),
+		progressbar.OptionSetWidth(progressBarWidth),
+		progressbar.OptionThrottle(progressBarThrottle),
+		progressbar.OptionOnCompletion(func() {
+			v.printfStderr("\n")
+		}),
+		progressbar.OptionSetRenderBlankState(true),
+	)
+}
+
 // isTerminal returns true if stdout is a terminal.
 // It checks whether v.Stdout implements Fd() (i.e. is an *os.File),
 // and falls back to false for non-file writers (e.g. in tests).