messages: pure builders for every event the bridge sends

src/messages builds Response, StateReport, DeferredResponse, ErrorResponse, ChangeReport and the scene, doorbell
and simple events from plain values; messageId and times are parameters, so a test compares whole objects.
StateBuilder collects properties checked by the descriptors, AlexaError and AlexaErrors carry the payload fields
of an error type. AlexaStatusMessage and AlexaErrorResponse move to src/compat and are written on the builders.
On the wire, against 1.5.2: a DeferredResponse has no context key, a ChangeReport has no correlationToken, the
namespace of an ErrorResponse follows its type, and a ChangeReport without a changed property is not published:
send() resolves "" and the bridge reports an error that names the endpoint.
143 tests pass (108 before).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/messages/index.ts

@@ -0,0 +1,18 @@
+// The messages of the bridge without the bridge: builders, the state collector and the errors.
+export {
+  changeReport, deferredResponse, doorbellPress, errorResponse, response, sceneEvent, simpleEvent, stateReport,
+  MessageError,
+} from "./build.js";
+export type {
+  ChangeReportFields, DoorbellPressFields, ErrorResponseFields, ResponseFields, SceneEventFields, SimpleEventFields,
+} from "./build.js";
+export { AlexaError, AlexaErrors, errorNamespace } from "./errors.js";
+export type { ChargeState, ControlUnavailableReason, CurrentDeviceMode } from "./errors.js";
+export { property } from "./property.js";
+export type { PropertyOptions } from "./property.js";
+export { StateBuilder } from "./StateBuilder.js";
+export type { StateBuilderOptions, Target } from "./StateBuilder.js";
+export type {
+  ChangeCause, ChangeReportMessage, Context, DeferredResponseMessage, Endpoint, ErrorResponseMessage, Event, Header,
+  ProactiveEventMessage, Property, ResponseMessage, SceneEventMessage,
+} from "./types.js";