Given the bugs that sentence detection in textextracts, let's migrate hovercards to use exintro instead of exchars for the summary.
- Request 525 characters
- Use exintro on the query, otherwise exchars will return unparsed wikitext from followup sections
Adjust the currently oversimplified approach of overflow: hidden (which cuts sentences off mid word) to use text-overflow: ellipsis (which has a better tradeoff of ellipsizing things midword).
- Moved to T136283 as it is a new feature and it doesn't block test/initial rollout.