feat(server): room-create accepts profile

Wires the T17 protocol's optional modifier profile through the server's room-create flow:

- rooms.Room gains an optional profile field; RoomRegistry.createRoom/joinRoom accept and echo it.

- GameSession constructor + GameSessionRegistry.create pass the profile through to ChessEngine's EngineOptions so modifier facts get seeded and the integration preset auto-activates at game start.

- broadcast.handleRoomCreate validates an inline profile via chess's validateProfile against the resolved layout, mapping validator codes (E_PROFILE_*) onto the wire protocol's MODIFIER_PROFILE_* family. Invalid profiles produce a non-fatal error and leave room / session state untouched; the creator is not bound.

- room.created and room.joined echo the active profile when present, so late joiners render piece modifier badges on first paint.

- RoomCreatedPayloadSchema and RoomJoinedPayloadSchema gain matching optional profile fields.

- @paratype/chess barrel: re-exports CaptureFlag + validateProfile + ModifierValidation* types so the server can consume them without reaching into internals.

Tests: 5 new cases (happy path, join echo, backward compat, INVULN_KING rejection, layout-invalid precedence). Full check green (1213/1213).

packages/chess/src/index.ts

@@ -18,6 +18,7 @@ export {
 export {
   GAME_ENTITY,
   PROMOTION_PIECES,
+  CaptureFlag,
   oppositeColor,
   chessFact,
   type PieceType,
@@ -73,3 +74,11 @@ export type {
   ModifierKindId,
   Direction,
 } from "./modifiers/types.js";
+export { validateProfile } from "./modifiers/validate.js";
+export type {
+  ValidationError as ModifierValidationError,
+  ValidationWarning as ModifierValidationWarning,
+  ValidationResult as ModifierValidationResult,
+  ValidationErrorCode as ModifierValidationErrorCode,
+  ValidationWarningCode as ModifierValidationWarningCode,
+} from "./modifiers/validate.js";