The tiptap-markdown extension was registered with default config, where
`transformPastedText` defaults to false. As a result, pasting markdown
text into card descriptions resulted in literal characters (e.g. '# heading'
shown as a paragraph of text) rather than rendered formatting.
Typing markdown shortcuts in the editor already worked because that goes
through a different path. Programmatic writes via the API also work
because they bypass the editor entirely. Only paste was affected.
Enabling `transformPastedText: true` makes pasted markdown behave as
users intuitively expect, matching the typed-markdown UX.
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>