Fix: only restore focus on push close when focus was inside the push (fixes #869)

[swashbuck]

Fixes #869

Fix

notifyPushView.closePush() now only calls a11y.gotoPreviousActiveElement() when focus was actually inside the push element at close time. Push notifications never grab focus on open (non-modal <dialog>, aria-modal=\"false\"), so an auto-close where the user never tabbed in has no focus contract to restore. The unconditional restore was sending focus to Adapt.navigation (navbar) when the previous active element was no longer readable (e.g. a clicked button that was hidden after click) - see #869 for the full repro via adapt-contrib-trickle PR #233.

Testing

1. Apply this branch in your core submodule.
2. Use a course with adapt-contrib-trickle configured with _styleAfterClick: \"hidden\" (default) on a block, the issue/232 branch of trickle, and an additionalContentLoaded globals message so notify.read is called.
3. Click the trickle Continue button via keyboard / screen reader. Confirm: "Loading" announce plays, focus does not jump to navbar, focus lands on the next block once content is ready.
4. Re-run the existing push notification interactions you rely on (badges, manual close button, Esc key) and confirm no regressions:
   • Auto-close with no user focus in push - focus stays where it is.
   • User clicks the close button - focus restores via gotoPreviousActiveElement.
   • User presses Esc with focus inside the push - focus restores.
   • User clicks the push body (_openNotifyOnClick) - separate popup handles its own focus contract.

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Posted via collaboration with Claude Code