fix(ui): re-export PublicToolbarItemId from superdoc/ui (SD-2920) (#3135)

The toolbar-and-commands docs page (apps/docs/editor/custom-ui/
toolbar-and-commands.mdx) tells consumers to import PublicToolbarItemId
from superdoc/ui as the typed source of truth for command ids. SD-2920
shipped BUILT_IN_COMMAND_IDS at runtime through that path but never
re-exported the derived type, so consumers writing
`import type { PublicToolbarItemId } from 'superdoc/ui'` couldn't
actually find it from the documented entry. They had to dip into
superdoc/headless-toolbar instead.

skipLibCheck: true on most consumer tsconfigs masked the broken
re-export from typecheck signal. The dist now exposes the type
through the same barrel as BUILT_IN_COMMAND_IDS, matching what the
docs already promise.

Author: caio-pizzol

packages/super-editor/src/ui/index.ts

@@ -19,6 +19,7 @@
 export { createSuperDocUI } from './create-super-doc-ui.js';
 export { shallowEqual } from './equality.js';
 export { BUILT_IN_COMMAND_IDS } from '../headless-toolbar/types.js';
+export type { PublicToolbarItemId } from '../headless-toolbar/types.js';
 
 // Re-export the document-side shapes the controller surfaces so
 // consumers can type their components without reaching into the