Moves verifySignature, signMessage, generateKeyPair and utility functions
from Yonexus.Client into Protocol so Server no longer depends on Client
at build time or runtime.
- Add encodeBuiltin/decodeBuiltin for builtin message wire format
- Add parseRuleMessage/parseRewrittenRuleMessage for rule dispatch
- Add type-safe envelope builders for all builtin message types
- Export codec module from index.ts