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>

dist/esm/messages/property.d.ts

@@ -0,0 +1,16 @@
+import type { Property } from "./types.js";
+export interface PropertyOptions {
+    /** The instance of a generic controller: "Blind.Lift". */
+    instance?: string;
+    /**
+     * When the value last changed. Default: now. message-guide.html, "Property object": "don't set the same
+     * timeOfSample value for all properties", so a device that knows when each value changed passes it.
+     */
+    timeOfSample?: string | Date;
+    /** How old the value may be, for a device that is polled. Default: 0. */
+    uncertaintyInMilliseconds?: number;
+}
+/** A time as Alexa wants it: ISO 8601 in UTC. Text is taken as given. */
+export declare function isoTime(time?: string | Date): string;
+/** One property of a context or of a change, its fields in the order of the examples. */
+export declare function property(namespace: string, name: string, value: unknown, options?: PropertyOptions): Property;