Fix legacy P2PKH singlesig address verification

[etherbiswas]

Description

This PR fixes legacy P2PKH address verification when verifying addresses derived from singlesig descriptors.

Previously, get_multisig_address() only allowed legacy descriptors when descriptor.is_basic_multisig was true:

if descriptor.is_segwit or (descriptor.is_legacy and descriptor.is_basic_multisig):

This prevented valid legacy singlesig descriptors from being verified and resulted in the error:

p2pkh address verification not yet implemented!

The fix allows legacy descriptors to be derived regardless of whether they are multisig:

if descriptor.is_segwit or descriptor.is_legacy:

Testing

I reproduced the issue on a physical SeedSigner Pi0 Smartcard build using a Satochip card configured with legacy (P2PKH) addresses.

Before the change:

• Address verification failed with:

  • p2pkh address verification not yet implemented!

After the change:

• Legacy singlesig addresses verify successfully.
• Existing SegWit verification behavior remains unchanged.

Screenshots

No UI changes were made.

[ ] Raspberry Pi OS Manual Build
[x] SeedSigner OS on a Pi0/Pi0W board
[ ] Other

[x] Bug fix
[ ] New feature
[ ] Code refactor
[ ] Documentation
[ ] Other

[etherbiswas]

@3rdIteration please Review src/seedsigner/views/seed_views.py for the acutal patch.

[etherbiswas]

Address verification currently also only had multisig support only, when singlesig was being used the resultant behavior was skipping, refer commit 7431683