fix: restore focus on toast dismiss

[mikeharv]

The basics

• I validated my changes

The details

Resolves

Fixes #8912

Proposed Changes

When a toast is dismissed via the close button, focus is restored to the node that was focused before the close button took focus, instead of always calling workspace.markFocused().

Screen.Recording.2026-08-11.at.12.39.27.PM.mov

To do this, a new FocusManager.getPreviouslyFocusedNode() method was created. We fall back to focusTree(workspace) if there is no focsuable previous node, so focus is parked on the workspace through FocusManager.

Reason for Changes

Previously, manually dismissing a toast always focused the workspace SVG. If the user had a block or other node focused, that context was lost.

Test Coverage

• focus_manager_test.js: getPreviouslyFocusedNode() gets a basic unit test
• toast_test.js new suite:
  • Restores a previously focused block after closing the toast.
  • Falls back to the workspace focus target when nothing was previously focused.