Add a "don't truncate" toggle for fields in the card preview editor

[thupsi]

Currently, card previews truncate field content by default. There should be an option to let a field's content display in full instead.

Use case: I use a nested "two column section: text with image" entry inside a CKEditor field. Right now, the author has to open the slideout just to read text that's actually part of the larger prose content. Truncation gets in the way of using CKEditor for these kinds of nested layouts, even though this is a fairly common pattern in long-form, text-driven content.

Proposal: Add a per-field toggle in the card preview editor that turns off truncation for that field, so its content can appear in full.

I know this is already possible with generated fields, but setting one up just to disable truncation feels like overkill for something this simple.

It would be great if this could ship alongside my other feature request too.