fix verify_signed_message and tests/robots/1/signed_message

[jerryfletcher21]

What does this PR do?

verify_signed_message was not checking for the validity of the signature. The documentation of python-gnupg is not clear about this, it says that the fields returned by verify are set just if the signature is valid. In this case tests/robots/1/signed_message was signed with the correct key but with the wrong digest-algo (SHA256 instead of SHA512) as expressed on the signature.
Running gpg --verify tests/robots/1/signed_message after importing the key returned:

gpg: WARNING: signature digest conflict in message
gpg: Can't check signature: General error

and a non zero error code. Changing Hash: SHA256 in tests/robots/1/signed_message returned no errors.

verify_signed_message called in test_verify_signed_message in api/tests/test_utils.py was not catching this because verified.fingerprint was set even though verified.valid was False.

I have recreated the signature with SHA512 by running:

gpg --pinentry-mode loopback --passphrase-file tests/robots/1/token --import tests/robots/1/enc_priv_key

cat tests/robots/1/signed_message | head -n 4 | tail -n 1 | gpg --armor --digest-algo SHA512 --clearsign --local-user "$(gpg --show-key tests/robots/1/pub_key | head -n 2 | tail -n 1)" --pinentry-mode loopback --passphrase-file tests/robots/1/token > tests/robots/1/signed_message

Checklist before merging

• Install pre-commit and initialize it: pip install pre-commit, then pre-commit install. Pre-commit installs git hooks that automatically check the codebase. If pre-commit fails when you commit your changes, please fix the problems it points out.

[Reckless-Satoshi]

Thanks for figuring this super sneaky one @jerryfletcher21 !

This PR needs a lot of testing as we risk getting all invoices submitted rejected.

[KoalaSat]

Test passing https://github.com/RoboSats/robosats/actions/runs/11418567681

[KoalaSat]

I managed to run an entire trade workflow with the Coordinator image generated from this commit https://hub.docker.com/layers/recksato/robosats/9e442c3/images/sha256-64343a7dc5b7c7b8805fc9e60ee8d74020c34da4a028a5c02ca492d48d9ce81a?context=explore