Curb excessive polling

[annybs]

Account and balance polling takes place every 5 seconds, which is far more frequent than is actually needed in practice - these should be slowed down to once per minute at most.

Additionally, many pages include 5-second polling intervals for data that is relatively static. This type of polling should be removed entirely, and only activated when there is an ongoing event - for example, refreshing the server list when there is a server task running.

[annybs]

I've slowed down the global, high-frequency background polling in b75c595

Balance and session checks will now occur once per minute, rather than every 5 seconds.