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/split.go

@@ -20,7 +20,7 @@ type SplitOptions struct {
 }
 
 type SplitResult struct {
-	Element *ui.Element
+	Element ui.Element
 	Changed bool
 }
 
@@ -28,7 +28,7 @@ type SplitResult struct {
 func Split(c *ui.Context, size *int, o SplitOptions, first, second func()) SplitResult {
 	k := pixel.K(c)
 	least := pixel.Or("Split Min", o.Min, 24)
-	var e *ui.Element
+	var e ui.Element
 	var total float32
 	back, fwd := ui.KeyLeft, ui.KeyRight
 	if o.Vertical {
@@ -47,7 +47,7 @@ func Split(c *ui.Context, size *int, o SplitOptions, first, second func()) Split
 	start := *size
 	e.AlignItems(ui.Stretch).Children(func() {
 		pane := ui.Box(c).Clip().Children(first)
-		shell, base, st := pixel.Shell(c, func() *ui.Element {
+		shell, base, st := pixel.Shell(c, func() ui.Element {
 			cur := ui.CursorResizeEW
 			if o.Vertical {
 				cur = ui.CursorResizeNS