BIP 360 (P2MR) implemented in Bitcoin Core on regtest: vector results, measurements, spec feedback

The recent updates concerning the pqc vector adjustments have been successfully implemented, enhancing the stability and functionality of the system. The corrections made to the pqc vectors, specifically noted in the GitHub merge request at bitcoin/bips2220, have resolved the previously identified KnownVectorBug exceptions. This fix has led to all 16 construction vectors now passing their tests without any issues, marking a significant improvement in the system's reliability.

Furthermore, the spend-path vectors, which were initially discussed, have now been formalized into a pull request at bitcoin/bips2232. The structure of these vectors adheres to the framework established by BIP 341's wallet-test-vectors.json. This includes a detailed setup featuring one six-input transaction to represent valid cases alongside nine transactions designed to illustrate failure paths. This meticulous generation and validation process carried out from the same branch ensures consistency and accuracy, aligning with the published construction vectors for thorough cross-verification. This development not only streamlines the testing process but also reinforces the integrity of transaction handling within the system.