buildDefaultActionItems

Build the default action list for an editor.

Every menu, toolbar and shortcut in the default chrome renders from this list rather than calling the editor directly, which is what makes TLUiOverrides.actions a real override point: relabel an entry, rebind its key or delete it and it changes — or disappears — everywhere at once.

## Why nothing here reads the editor The list is built once per editor, not once per frame, so anything read while building it would be frozen at that moment — an item marked disabled because nothing was selected when the chrome mounted would stay disabled forever. Availability is therefore *not* baked in: it is resolved where it is rendered, by useActionState, which reads the editor reactively. Everything below is either a constant or a closure.