Upgrade MyGo to v0.5.5

Elements are now pass-scoped value handles: tests that read bounds
after a frame bind a ui.Handle. pixel tells frames apart by the build
pass's root, since the Tester clock no longer moves on its own.

Fix the regressions the upgrade brought:
- Clipboard reads in input handlers go through c.Services().
- MyGo notes an overlay's opener after building it, so AutoFocus
  inside lost it; pixel.AutoFocus focuses through a Handle, and
  archtest bans the raw call. Dialogs hand the focus back again.
- Elements around a press stay hovered: Tooltip tells a press-given
  focus by focus arriving under the pointer.
- The web host moves the Tester clock with real time, at most 500 ms
  a call, and gives components the real clock.

The gallery's source index also accepts CRLF checkouts.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

overlay/tooltip.go

@@ -15,7 +15,7 @@ type TooltipOptions struct{}
 const tipWidth = 160
 
 // Tooltip bubbles text after 500 ms, or on keyboard focus.
-func Tooltip(c *ui.Context, text string, o TooltipOptions, trigger func()) *ui.Element {
+func Tooltip(c *ui.Context, text string, o TooltipOptions, trigger func()) ui.Element {
 	k := pixel.K(c)
 	wrap := ui.Box(c)
 	show := hint(c, wrap, 500*time.Millisecond)
@@ -32,12 +32,12 @@ func Tooltip(c *ui.Context, text string, o TooltipOptions, trigger func()) *ui.E
 }
 
 // bubble floats content by b; w keeps it inside.
-func bubble(c *ui.Context, b ui.Rect, content func(), w int) *ui.Element {
+func bubble(c *ui.Context, b ui.Rect, content func(), w int) ui.Element {
 	k := pixel.K(c)
 	ww, wh := c.Size()
 	x := max(0, min(b.X+b.W/2-k.D(8), ww-k.D(w)))
 	at := max(3, int((b.X+b.W/2-x)/k.Dot()))
-	var e *ui.Element
+	var e ui.Element
 	ui.Overlay(c, func() {
 		e = ui.Box(c).Absolute().Left(x).PassThrough()
 		tail := display.Bottom