* Add $:/core/templates/plain-text core template
This template renders a single `text` variable as plain text using the
<$text> widget. It enables exporting and downloading dynamic strings
via messages like `tm-download-file` using the `variables` paramObject,
eliminating the need to create temporary tiddlers in the wiki store
purely for rendering purposes.
* add release note
* add rendered text template
* update change note