Adds wire schemas and error codes for the modifier-profile feature:
- ModifierProfileSchema mirrored in server/protocol.ts (server pins a different zod major, so the chess-side schema cannot be re-exported directly). A keyof parity check guards against drift.
- RoomCreatePayloadSchema gains an optional 'profile' field — additive, existing callers unaffected.
- modifier-profile.update (client->server) payload schema with roomCode, newProfile, and version (for optimistic-concurrency checks).
- modifier-profile.updated (server->client) broadcast payload interface, typed for future promotion to the discriminated union when the broadcast is wired through rooms.
- Four new error codes: MODIFIER_PROFILE_INVALID / NO_KING / INVULN_KING / DEADLOCK, exported as const literals alongside the enum.
- Client wire types (packages/chess/src/net/types.ts) mirror all of the above: ModifierProfileWire shape, optional 'profile' on Room{Create,Created,Joined} payloads, and the new modifier-profile.* client/server message envelopes.
- PROTOCOL.md documents the new request/response flow and extends the error-code table.
Tests: 20 new cases across ModifierProfileSchema, RoomCreate profile integration, ModifierProfileUpdatePayloadSchema, and error-code acceptance.
Joey Yakimowich-Payne
4b7d943edc