Rethink teaching tip editing UI (pill display is unworkable)

[yvanvds]

In the leerdoelen editor, teaching tips are rendered as pills. This has two problems:

• Long tips overflow the pill layout and look bad.
• The pill form makes it impossible to edit an existing tip in place — the only available action is to delete it and retype from scratch.

We need to rethink the UI for managing teaching tips so that:

• Long text is displayed in a readable way (wrapping, list rows, or a dedicated detail view).
• Existing tips can be edited in place without losing the original content.