Migrate all btcd dependencies to the new per-package v2 modules (wire/v2,
txscript/v2, chaincfg/v2, chainhash/v2, btcutil/v2, psbt/v2, btcec/v2)
introduced by btcd v0.26.0, and pin the tagged ecosystem versions:
btcwallet v0.17.0, neutrino v0.18.0 and lightning-onion v1.4.0.
The bulk of the import rewrite was produced by the scripted diff from
https://github.com/btcsuite/btcd/pull/2547 (followed by 'make rpc'). The
address symbols that moved out of btcutil into the new address package
are imported as btcaddr where a local "address" variable would otherwise
shadow them. The go.mod/go.sum updates and the remaining manual
compilation fixes are folded into this single commit so it builds on its
own (the migration was previously split into a reproducible scripted-diff
plus follow-ups, intended to be squashed on merge).
