Unlike bitcoinjs-lib's native psbt.signInput(), this function automatically detects
if the input is a Taproot input and internally tweaks the key if needed.
This behavior matches how signInputBIP32 works, where the BIP32 node is automatically
tweaked for Taproot inputs. In contrast, bitcoinjs-lib's native implementation requires
manual pre-tweaking of ECPair signers for Taproot inputs.
Signs a specific input of a PSBT with an ECPair.
Unlike bitcoinjs-lib's native
psbt.signInput(), this function automatically detects if the input is a Taproot input and internally tweaks the key if needed.This behavior matches how
signInputBIP32works, where the BIP32 node is automatically tweaked for Taproot inputs. In contrast, bitcoinjs-lib's native implementation requires manual pre-tweaking of ECPair signers for Taproot inputs.