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>

code/guards_test.go

@@ -115,9 +115,9 @@ func TestCrashScreenStepsAtFourFPS(t *testing.T) {
 	tt := view(600, 300, wd, func(c *ui.Context) {
 		code.CrashScreen(c, "panic: oops", nil, code.CrashScreenOptions{})
 	})
-	// Paint asks for the next step on the real clock.
+	// Paint asks for the next step on the frame clock.
 	pixel.ResetDue()
-	before := time.Now()
+	before := tt.Now()
 	tt.Frame()
 	if d := pixel.Due().Sub(before); d < time.Second/4 || d >= time.Second/2 {
 		t.Fatalf("the next blink step is %v away, want a quarter second", d)