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/fieldset.go

@@ -9,7 +9,7 @@ import (
 type FieldsetOptions struct{}
 
 // Fieldset frames a group of fields under a legend.
-func Fieldset(c *ui.Context, legend string, o FieldsetOptions, content func()) *ui.Element {
+func Fieldset(c *ui.Context, legend string, o FieldsetOptions, content func()) ui.Element {
 	k := pixel.K(c)
 	lw := pixel.Measure(legend)
 	return ui.Column(c).Padding(k.D(pixel.LineHeight), k.D(8), k.D(8), k.D(8)).Gap(k.D(6)).Role(ui.RoleGroup).Label(legend).Draw(func(p *ui.Painter, r ui.Rect) {