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/checkboxgroup.go

@@ -14,7 +14,7 @@ type CheckboxGroupOptions struct {
 }
 
 type CheckboxGroupResult struct {
-	Element *ui.Element
+	Element ui.Element
 	Changed bool
 }
 
@@ -38,7 +38,7 @@ func CheckboxGroup(c *ui.Context, text string, items []string, checked []bool, o
 	all := count(checked) == len(checked) && len(checked) > 0
 	res := CheckboxGroupResult{}
 	res.Element = ui.Column(c).Gap(k.D(2)).Role(ui.RoleGroup).Children(func() {
-		shell, base, st := pixel.Shell(c, func() *ui.Element {
+		shell, base, st := pixel.Shell(c, func() ui.Element {
 			return ui.CheckboxBase(c, &all).Label(text).Disabled(o.Disabled)
 		})
 		shell.Size(k.D(12+pixel.Measure(text)), k.D(pixel.LineHeight)).Draw(func(p *ui.Painter, r ui.Rect) {