Upgrade MyGo to v0.5.5

MyGo v0.5.5 returns ui.Element as a checked value handle instead of a
pointer. Migrated with `mygo migrate-ui`, then fixed what the codemod
leaves to review:

- Element nil checks become .Valid(); absent elements are ui.Element{}.
- Input handlers and paint callbacks run outside the build pass, where
  elements expire and Context methods are inert: read IsDisabled into a
  local during the build, keep a ui.Handle for Focus, use c.Services()
  for clipboard access, create ui.Local state during the build.
- Add core.AutoFocus: v0.5.5 records an overlay's opener after its
  content builds, so same-frame autofocus lost focus restore on close.
  It focuses one frame later; cascader rows defer their focus likewise.
- core.OverlayLayer identifies build passes by the root element, not
  c.Now(), which repeats across passes and under the Tester clock.
- Context menus survive the opening press counted as PressedOutside;
  split button tooltip no longer reorders its open menu; disabled
  menubar rows pass presses to the panel; Form defers blur-started
  async checks so the growing message no longer moves Submit away
  from the release; Combobox drops its disabled copy now that MyGo
  blocks typing under a disabled wrapper (canary flipped to a guard).
- The Tester clock is virtual: tests use Advance/Now instead of
  time.Sleep/time.Now and read element state inside the view. The web
  mirror advances the clock to wall time before each frame and input.
- AGENTS.md and docs describe the value Element API and the new pin.

Snapshot goldens are darwin-only and were not re-verified here.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

account/api_key_manager.go

@@ -57,7 +57,7 @@ type ApiKeyManagerOptions struct {
 
 // ApiKeyManagerResult reports creation and revocation requests.
 type ApiKeyManagerResult struct {
-	Element        *ui.Element
+	Element        ui.Element
 	create, revoke string
 }
 
@@ -102,7 +102,7 @@ func ApiKeyManager(c *ui.Context, s *ApiKeyManagerState, keys []APIKey, opts Api
 		}
 		accountRows(c, len(keys), func(i int) any { return keys[i].ID }, func(i int) {
 			key := keys[i]
-			ui.Row(c).Key(key.ID).MinHeight(d.ControlHeight()+d.Unit()*4).Gap(d.Unit()*3).AlignItems(ui.Center).
+			ui.Row(c.Key(key.ID)).MinHeight(d.ControlHeight()+d.Unit()*4).Gap(d.Unit()*3).AlignItems(ui.Center).
 				BorderWidth(0, 0, theme.BorderWidth, 0).BorderColor(k.Border).Children(func() {
 				ui.Column(c).Grow(1).MinWidth(0).Gap(2).Children(func() {
 					ui.Text(c, key.Name).FontWeight(600).SingleLine()
@@ -191,7 +191,7 @@ func apiKeyCreateDialog(c *ui.Context, s *ApiKeyManagerState, disabled bool) (st
 		}
 		res := input.TextInput(c, &s.name, input.TextInputOptions{Label: core.Msg(c, "api_key_manager.name"), Placeholder: core.Msg(c, "api_key_manager.name"),
 			Disabled: s.pending, Error: s.err})
-		res.Input.AutoFocus()
+		core.AutoFocus(c, res.Input)
 		if res.Submitted() && strings.TrimSpace(s.name) != "" && !s.pending {
 			asked = true
 		}