Support for lnurlp:// URI scheme and nested LIGHTNING:lnurlp://

[AxelHamburch]

Description:

Currently, Alby Go Wallet supports:

• lightning: URI scheme for Lightning invoices

However, it does not support:

• lnurlp:// URI scheme for LNURL-pay
• nested/compound URI schemes where both are combined

Example of unsupported formats:

lnurlp://demo.lnbits.com/bitcoinswitch/api/v1/lnurl/b4dEpKaanBbk7DmEoia32D?pin=13
LIGHTNING:lnurlp://demo.lnbits.com/bitcoinswitch/api/v1/lnurl/b4dEpKaanBbk7DmEoia32D?pin=13

Expected Behavior:
When scanning a QR code with lnurlp:// or nested LIGHTNING:lnurlp:// format, Alby Go should:

1. Recognize the lnurlp:// URI scheme
2. For nested format: strip the outer lightning: prefix and process the inner lnurlp:// URL
3. Process the LNURL-pay request as normal

Current Behavior:
Alby Go does not recognize or handle these formats and fails to process the payment request with the error:

Use Case:
Many Lightning payment systems, particularly LNbits and its extensions, generate QR codes with lnurlp:// and nested LIGHTNING:lnurlp:// formats. The nested format provides better compatibility with legacy wallets that only recognize the lightning: prefix. Supporting these formats would improve interoperability with LNbits-based payment systems and align with industry standards.

Proposed Solution:

1. Add support for lnurlp:// URI scheme
2. Add URI parsing logic to handle nested LIGHTNING:lnurlp:// format by stripping the outer lightning: prefix
3. Process the LNURL-pay request as a standard LNURL-pay flow

Additional Context:
WoS and Phoenix already support lnurlp:// and the nested URI scheme.