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>

input/button.go

@@ -20,9 +20,9 @@ type ButtonOptions struct {
 }
 
 type ButtonResult struct {
-	Element *ui.Element
+	Element ui.Element
 	// Base is the focusable inside Element.
-	Base    *ui.Element
+	Base    ui.Element
 	Clicked bool
 }
 
@@ -31,7 +31,7 @@ func Button(c *ui.Context, text string, o ButtonOptions) ButtonResult {
 	k := pixel.K(c)
 	h, pad, top, sc := o.Size.metrics()
 	name := label(o.Label, text)
-	shell, base, st := pixel.Shell(c, func() *ui.Element {
+	shell, base, st := pixel.Shell(c, func() ui.Element {
 		return ui.ButtonBase(c).Label(name).Disabled(o.Disabled || o.Loading)
 	})
 	w := pixel.Measure(text) * sc