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/StateBuilder.js

@@ -0,0 +1,66 @@
+import { EndpointHealth } from "../registry/interfaces/EndpointHealth.js";
+import { SchemaError } from "../registry/schema.js";
+import { property } from "./property.js";
+/**
+ * Collects the properties of one message. For a Response or a StateReport they are its context. For a ChangeReport
+ * changed() and unchanged() say which of the two lists the properties that follow belong to.
+ */
+export class StateBuilder {
+    constructor(options = {}) {
+        this.lists = { context: [], change: [] };
+        this.target = options.target ?? "context";
+        this.now = options.now ?? (() => new Date());
+    }
+    /**
+     * A property of an interface the library describes, its value checked: set(PowerController, "powerState", "ON").
+     * Given a capability of a device in place of the interface, the property carries the instance of the capability.
+     * Throws SchemaError for a value Alexa would not take.
+     */
+    set(source, name, value, options = {}) {
+        const descriptor = "descriptor" in source ? source.descriptor : source;
+        const instance = options.instance ?? ("descriptor" in source ? source.instance : "");
+        const where = `${descriptor.namespace}${instance ? ` "${instance}"` : ""}: ${name}`;
+        const described = descriptor.properties[name];
+        if (!described) {
+            const names = Object.keys(descriptor.properties);
+            throw new SchemaError(where, names.length > 0
+                ? `not a property of the interface, which has ${names.join(", ")}`
+                : "the library knows no property of the interface, report it with setRaw()");
+        }
+        if (descriptor.instanced && !instance) {
+            throw new SchemaError(where, "the interface has instances, pass the one that is reported: { instance: \"Blind.Lift\" }");
+        }
+        return this.setRaw(descriptor.namespace, described.name, described.value.parse(value, where), { ...options, instance });
+    }
+    /** A property as given, nothing checked: for an interface or a value the library does not describe. */
+    setRaw(namespace, name, value, options = {}) {
+        return this.add(property(namespace, name, value, { ...options, timeOfSample: options.timeOfSample ?? this.now() }));
+    }
+    /** The connectivity of Alexa.EndpointHealth, which belongs in every report of an endpoint that declares it. */
+    health(value, reason, options = {}) {
+        return this.set(EndpointHealth, "connectivity", reason ? { value, reason } : { value }, options);
+    }
+    /** A property built elsewhere, to the list that is filled now or to the one named. */
+    add(built, target = this.target) {
+        this.lists[target].push(built);
+        return this;
+    }
+    /** The properties that follow are the ones that changed. */
+    changed() {
+        this.target = "change";
+        return this;
+    }
+    /** The properties that follow did not change: a ChangeReport lists them in its context. */
+    unchanged() {
+        this.target = "context";
+        return this;
+    }
+    /** The properties for the context of the message, in the order they were set. */
+    get context() {
+        return [...this.lists.context];
+    }
+    /** The properties for payload.change of a ChangeReport. */
+    get change() {
+        return [...this.lists.change];
+    }
+}