feat: increase seqnum

[andreabadesso]

Motivation

When users call GET /wallet/address/info to get seqnum before submitting nano contract transactions, the daemon syncs events slowly, so multiple rapid calls return the same seqnum, causing transaction conflicts.

Acceptance Criteria

• txProposalCreate increments the caller address's seqnum when the transaction is a nano contract
• The increment happens atomically within the existing transaction block alongside tx proposal creation and UTXO marking

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged
• Make sure either the unit tests and/or the QA tests are capable of testing the new features
• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.