processUpdate

Process transaction update from subscription.

Handles both transaction updates (with UTXO changes) and progress updates.

For transaction updates (based on status):

• SUCCESS/PARTIAL_SUCCESS:

1. Insert created UTXOs (state = AVAILABLE)

2. Mark spent UTXOs as SPENT (permanent)

• FAILURE:

1. Don't insert created UTXOs (never created on-chain)

2. Unlock spent UTXOs (PENDING → AVAILABLE) so they can be reused

For progress updates:

• Just return (nothing to do with UTXOs)

Parameters