Ensure double-click opens card instead of opening sidebar

In this video, the user attempts to double-click on a subsection. The first click opens the sidebar, which causes a layout update, and prevents the double-click from registering (since the layout reflows, second click is on the sidebar).

This may be able to be fixed with a brief pause after a single click. In other words, for a typical double-click threshold of ~500ms:

1.(0ms) Click event on the card registers
2. (0ms) Timer for 500ms begins
3. (0ms-500ms) If a double-click event is registered on the card, the timer is canceled
4. (500ms) The sidebar opens at the end of the timer, if no double-click was registered

The threshold may need some tuning. I don't think it's possible to detect the user's double-click delay, so there's a potential accessibility concern (we want any users with a longer double-click time to still be able to double-click if possible). There's also a potential performance concern (500ms is above the general recommended perceptual delay threshold, so we may want to adjust downwards if it doesn't feel responsive).

Related Issues

#1883
#1598

(Follow-up based on feedback at Open edX 2025, thanks @ormsbee for highlighting this)