Add z-image image generation prototype (#13659)

progress/stepbar.go

@@ -0,0 +1,33 @@
+package progress
+
+import (
+	"fmt"
+	"strings"
+)
+
+// StepBar displays step-based progress (e.g., for image generation steps).
+type StepBar struct {
+	message string
+	current int
+	total   int
+}
+
+func NewStepBar(message string, total int) *StepBar {
+	return &StepBar{message: message, total: total}
+}
+
+func (s *StepBar) Set(current int) {
+	s.current = current
+}
+
+func (s *StepBar) String() string {
+	percent := float64(s.current) / float64(s.total) * 100
+	barWidth := s.total
+	empty := barWidth - s.current
+
+	// "Generating   0% ▕         ▏ 0/9"
+	return fmt.Sprintf("%s %3.0f%% ▕%s%s▏ %d/%d",
+		s.message, percent,
+		strings.Repeat("█", s.current), strings.Repeat(" ", empty),
+		s.current, s.total)
+}