Update go.mod module line, all require/replace directives, and every
.go import path from forge.lthn.ai/core/go-blockchain to
dappco.re/go/core/blockchain. Add replace directives to bridge
dappco.re paths to existing forge.lthn.ai registry during migration.
Update CLAUDE.md, README, and docs to reflect the new module path.
Co-Authored-By: Virgil <virgil@lethean.io>
Convert all remaining fmt.Errorf and errors.New in production code
to coreerr.E(). Covers crypto/ (keygen, signature, clsag, keyimage,
pow), consensus/block, and chain/ring. Only sentinel error definitions
in errors.go and varint.go retain errors.New (correct usage).
Co-Authored-By: Charon <charon@lethean.io>