Problem: can't determine if the progress bar stopped updating

This would be useful to know to stop displaying it after the user was shown
the progress bar to render to its end.

Solution: expose `IsComplete` method is based on what's been drawn

progress/progress.go

@@ -211,8 +211,7 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		}
 
 		// If we've more or less reached equilibrium, stop updating.
-		dist := math.Abs(m.percentShown - m.targetPercent)
-		if dist < 0.001 && m.velocity < 0.01 {
+		if !m.IsAnimating() {
 			return m, nil
 		}
 
@@ -362,6 +361,12 @@ func max(a, b int) int {
 	return b
 }
 
+// IsAnimating returns false if the progress bar reached equilibrium and is no longer animating.
+func (m *Model) IsAnimating() bool {
+	dist := math.Abs(m.percentShown - m.targetPercent)
+	return !(dist < 0.001 && m.velocity < 0.01)
+}
+
 func min(a, b int) int {
 	if a < b {
 		return a