Migrate types/asset.go from fmt.Errorf to coreerr.E() for consistency
with the rest of the types package. Add usage-example comments (AX-2) to
all key exported functions in consensus/, chain/, and types/ so agents
can see concrete calling patterns without reading implementation details.
Co-Authored-By: Virgil <virgil@lethean.io>
Expose generate/verify wrappers for generic_double_schnorr_sig and add a consensus helper for balance-proof checks.
Co-Authored-By: Charon <charon@lethean.io>
