Implement fast-path loading of future events

Until now, the event finder page will load events from the API for the required time period. On page load, the upcoming events are always displayed, so there is always a call to the API for future events being issued.

This commit removes one HTTP operation by bundling the upcoming events in the page response itself, as they will always be displayed anyway. This can save a few hundred milliseconds when loading over a slow network, where TLS handshake time is significant.