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/layout.go

@@ -29,7 +29,7 @@ func rule(g pixel.Canvas, x, y, n int, vertical bool, on, off int, s pixel.Slot)
 type dragKey struct{}
 
 // drag is enabled e's pointer travel this frame, in dots.
-func drag(k pixel.Kit, e *ui.Element) (dx, dy int, ok bool) {
+func drag(k pixel.Kit, e ui.Element) (dx, dy int, ok bool) {
 	rest := ui.Local(e, dragKey{}, func() [2]float32 { return [2]float32{} })
 	fx, fy, ok := e.Dragged()
 	if !ok || e.IsDisabled() {