Improve UX for adding workspace prompts and for prompt library

Available prompts are cutoff and it is unclear which is the prompt I want to select if several start with similar wording

Increases difficulty in getting users to adopt AI assistant

At least in the prompt library, improve the UI, in particular when in tile view.

1) Icons are too large, waste screen real estate. Use more of the space to contain a preview of the prompt.
2) Mousing over a card should reveal a more in-depth preview - currently it only shows the same truncated preview as visible from the initial add prompt drop-down