External signer setup: surface compiled-without-support state

[johnny9]

Gap

QML treats external signer support not being compiled in the same as no device being detected. Qt widgets explicitly disable the external signer UI with a compiled-without-support message.

Work

Add a QML-visible external-signer-support state and use it in settings and wallet creation so unsupported builds do not present misleading signer setup or no-device messages.

Code References

• qml/components/WalletSettings.qml:103
• bitcoin/src/node/interfaces.cpp:263
• bitcoin/src/qt/createwalletdialog.cpp:86
• bitcoin/src/qt/optionsdialog.cpp:141