Test Bitcoin signing with shared vectors

[benma-agent]

Consume the PSBT transaction vectors introduced by
BitBoxSwiss/bitbox02-firmware#2017 in
simulator signing tests. The PSBT conversion exercises the low-level
signing protocol without duplicating each vector as a raw request.

Centralize simulator stdout parsing and check versioned screens, errors,
signature insertion, generated outputs, and final transactions.

Close gaps exposed by the vectors: recognize Taproot policies when
loading previous transactions, preserve existing Taproot script-path
signatures, and forward silent-payment and payment-request metadata.

Remove obsolete transaction test helpers superseded by the vectors and
keep the simulator harness lint-clean.

[cedwies]

Apart from the rebase:

For the three vectors that the PSBT finalizer cannot finalize, the test currently stops after checking the signature’s shape, etc. Could we still calculate the relevant sighash from the original PSBT and cryptographically verify the returned signature against the expected public key?
This would not be as strong as finalizing the PSBT and executing the complete Bitcoin scripts, but it would still prove that the firmware signed the transaction of the original PSBT and therefore stronger than the current test for the 3 special vectors. Is there a limitation that prevents doing so?