Dynamically fetch taken order expiration from mostro info events

[bilthon]

The Countdown component in the /my-trades section (see figure below) is currently being used to showcase the remaining time a seller user has to pay an invoice or the buyer has to provide an invoice before the current trade is cancelled and the order is re-published for others to take. The time this countdown should run for, is currently hard-coded to 900 seconds. But this is actually a tunable parameter for the mostro operator, with 900 seconds being just the default value.

This and other parameters are currently being published by mostro in a specific even described here.

The web client is currently detecting this nostr event, parsing it and in the feat_key_rotation branch a JS event is actually being emitted. There's also a pinia store prepared for this here. But these two things are not currently connected.

Ideally we would have this mostro store be the source of this information for the Countdown progress bar value.