fix(rust-client): apply expiration_delta to requests without own output notes

[Bruce039]

Summary

Closes #2579.

TransactionRequestBuilder::expiration_delta was only applied through the SendNotes transaction script. A request without own output notes (consume, pswap cancel, bare build()) accepted the delta and then ran without a script, so the transaction never expired (expiration_block_num() == u32::MAX).

Changes

• TransactionRequest::build_transaction_script: when there is no script template and a non-zero expiration delta is set, return the standard ExpirationTransactionScript together with its tx_script_args(), so the kernel enforces the delta.
• Unit test expiration_delta_without_script_template_builds_expiration_script and mock-chain test expiration_delta_applies_to_request_without_own_output_notes, which fails on next with left: BlockNumber(4294967295) right: BlockNumber(13).
• CHANGELOG entry.

cargo nextest run -p miden-client --lib: 187 passed; miden-client-unit-tests: 143 passed; clippy clean.

[igamigo]

Thanks!