Share private state

We want to support a canonical mechanism of sharing private state.
Specifically, we need to define specs for a service where transmitters communicate with a service/transport layer that allows receivers in multiple different devices to reconstruct some private account's state.

In terms of what gets communicated, it would be nice if we could transmit the results of transactions individually. In this sense, what we currently apply to the store is the `TransactionStoreUpdate` (contains the executed transaction, but also metadata, notes that will be created in the future, tags to track, etc.). When receivers get these, they can apply the deltas on their clients and end up with the current account commitment.

Related to this is the transaction component refactor that is being discussed (https://github.com/0xMiden/miden-client/issues/984#issuecomment-3156562711).