Refactor: one colorFade transition replaces internal.Fade

textInputFade becomes colorFade in theme.go and serves AvatarGroup,
Image retry, Tag and EditableText, which used internal.Fade. MyGo already
skips element transitions under ReduceMotion, so dropping the Motion
check keeps behaviour.

text_input.go

@@ -72,9 +72,6 @@ func TextInput(c *ui.Context, value *string, opts TextInputOptions) InputResult
 	return r
 }
 
-// textInputFade eases hover, focus and error colors.
-var textInputFade = ui.ElementTransition{Colors: true, Duration: theme.StateDuration}
-
 // textInputLook is the state a field frame shows; disabled gains any disabled ancestor.
 type textInputLook struct {
 	disabled, readOnly, area bool
@@ -120,7 +117,7 @@ func textInputFrame(c *ui.Context, look *textInputLook, build func(frame *ui.Ele
 		case in.Focused() && !look.readOnly:
 			border = k.Focus
 		}
-		frame.Background(bg).Border(theme.BorderWidth, border).Transition(textInputFade)
+		frame.Background(bg).Border(theme.BorderWidth, border).Transition(colorFade)
 		frame.DrawOver(func(p *ui.Painter, r ui.Rect) {
 			if in.FocusVisible() {
 				internal.FocusRing(p, r, theme.ControlRadius, k.Focus)