This PR addresses a potential bug that appears only when 2 or more tabs are open, and all of them have a paring modal open.
In this scenario when a tab successfully pairs with a wallet, the others also correctly sync thanks to broadcast channel. However, beacon enters a broken state when closing all the open alerts because, in the tabs that never concluded the sync, they still have a pending proposal.
WC's ping gets dropped after a delay oft 30s. Added interval to generate a new one after expiration.