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>

layout/handheld.go

@@ -18,7 +18,7 @@ type HandheldOptions struct {
 }
 
 type HandheldResult struct {
-	Element                     *ui.Element
+	Element                     ui.Element
 	Up, Down, Left, Right, A, B bool
 }
 
@@ -69,7 +69,7 @@ func Handheld(c *ui.Context, o HandheldOptions, screen func()) HandheldResult {
 
 // key is a d-pad arm, or a round button.
 func key(c *ui.Context, k pixel.Kit, name string, x, y, w, h int, round, disabled bool) bool {
-	shell, base, st := pixel.Shell(c, func() *ui.Element { return ui.ButtonBase(c).Label(name).Disabled(disabled) })
+	shell, base, st := pixel.Shell(c, func() ui.Element { return ui.ButtonBase(c).Label(name).Disabled(disabled) })
 	shell.Absolute().Left(k.D(x)).Top(k.D(y)).Size(k.D(w), k.D(h)).Draw(func(p *ui.Painter, r ui.Rect) {
 		g := k.Canvas(p, r)
 		dy := 0