Content hovercards

Hovering over any content name (characters, locations, items) should pop up a detailed hovercard with information about that content at a glance, rather than having to click through and see things like name/description and other popular fields.

No file or test is named. Start by tracing the existing content-name rendering and click-through entry points for characters, locations, and items; done means hovering each supported name shows a consistent at-a-glance card with the name, description, and other popular fields.

Written by the indexing model from the issue text.