"Summary length" broken in Navigation Cards

Problem/Motivation

The "Summary length" option for Navigation Cards does not work as intended:

- When set to 0 the text fully disappears, despite the tooltip saying "Set to 0 for no limit."
- When set to a huge number, the text still gets cut off significantly earlier

Steps to reproduce

On any CivicTheme install,

1. Create a Navigation Card (for example in a Manual List) with a long Summary text
2. The text will be cut off after a while
3. Go to Appearance -> Settings -> CivicTheme -> Navigation Card and change "Summary length" to 0
4. The text will have completely dissapeared
5. Go to Appearance -> Settings -> CivicTheme -> Navigation Card and change "Summary length" to 10000
6. The text will still be cut at a convenient point (for example at the end of a phrase, in my case around 500 chars)

Proposed resolution

On the Slack channel, I was informed:

> It is not possible to disable this behaviour. This was done to make sure that the card always looks as per design and has some sensible limits.

Therefore, I suggest the tooltip text be changed to reflect this.

Remaining tasks

User interface changes

API changes

Data model changes