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/rangeslider.go

@@ -44,8 +44,8 @@ func RangeSlider(c *ui.Context, text string, low, high *float64, o RangeSliderOp
 }
 
 // knob is one draggable end, fenced by r.lo and r.hi.
-func knob(c *ui.Context, k pixel.Kit, track *ui.Element, v *float64, r rail, lo, hi float64, w int) {
-	shell, base, st := pixel.Shell(c, func() *ui.Element {
+func knob(c *ui.Context, k pixel.Kit, track ui.Element, v *float64, r rail, lo, hi float64, w int) {
+	shell, base, st := pixel.Shell(c, func() ui.Element {
 		return ui.Box(c).Focusable().Role(ui.RoleSlider).Label(r.label).Description(fmtValue(*v)).Disabled(r.disabled)
 	})
 	set := func(x float64) { *v = max(r.lo, min(r.hi, x)) }