build: dual CJS/ESM output, ES2020 target, Node 18 floor

"exports" gains "import" and "types" next to "require": import "alex2node" failed with
ERR_PACKAGE_PATH_NOT_EXPORTED. scripts/build.mjs compiles src/ to dist/cjs, dist/esm and dist/types in a staging
directory and swaps them in only when both compiler runs passed. "main" and "types" follow for resolvers that do
not read "exports". Target ES6 -> ES2020, "engines": node >= 18, relative imports carry ".js" for Node's ESM loader.
uuid gives way to crypto.randomUUID(); mqtt is the only runtime dependency left.

Tests load the package by name. New: both entry points, the modules the builds import, dist/ equal to a fresh
build, a round trip on the ES module build, and two compiled type fixtures in place of the .d.ts regexes.
22 tests pass in 5.7 s. dist/: 16 files, 79,711 B -> 25 files, 132,291 B; the npm tarball is 25,125 B.

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

dist/Alex2Node.d.ts

@@ -1,59 +0,0 @@
-import { IClientOptions } from "mqtt";
-import Device from "./Device";
-import { EventEmitter } from "events";
-import { DisplayCategory } from "./DisplayCategory";
-/** Optional settings for the bridge (1.5.1). Everything has the 1.4.0 behaviour as its default. */
-export interface Alex2MQTTOptions {
-    /** The broker URL. Default: the public Alex2MQTT broker, mqtt://Alex2MQTT.stormysdream.club:1883. */
-    host?: string;
-    /** Extra mqtt.js client options (reconnectPeriod, connectTimeout, clientId, ...). Merged over the defaults. */
-    mqtt?: IClientOptions;
-    /** Where log lines go. Default: console (only when debugLogging is on). */
-    log?: (message: string, detail?: unknown) => void;
-}
-export declare const DEFAULT_HOST = "mqtt://Alex2MQTT.stormysdream.club:1883";
-/**
- * The Alexa-to-MQTT bridge: one broker connection for a user's root topic, a set of registered devices, discovery and
- * directive dispatch.
- *
- * Events (all optional to listen to - since 1.5.1 a broker outage never throws out of the library):
- *   "connect"           connected (or reconnected) and subscribed to <root>/#
- *   "offline"           the connection dropped; mqtt.js reconnects on its own (reconnectPeriod, default 1 s)
- *   "reconnect"         a reconnect attempt starts
- *   "close"             the connection closed
- *   "error"   (err)     a connection or publish error. Emitted ONLY when a listener is attached (1.4.0 emitted it
- *                       unconditionally, and Node kills a process that has an unhandled "error" event)
- *   "discover" (n)      a discovery request was answered with n devices
- *   "directive" (info)  a directive was dispatched to a device: { endpointId, namespace, name }
- */
-declare class Alex2MQTT extends EventEmitter {
-    private username;
-    private password;
-    private rootTopic;
-    private debugLogging;
-    private client;
-    private devices;
-    private MqttHost;
-    private options;
-    /** true while the broker connection is up. */
-    connected: boolean;
-    /** ISO time of the last discovery request answered, null before the first. */
-    lastDiscoveryAt: string | null;
-    constructor(username: string, password: string, rootTopic: string, debugLogging?: boolean, options?: Alex2MQTTOptions);
-    private log;
-    /** Emit "error" only when somebody listens: an unhandled "error" event would crash the host process. */
-    private fail;
-    connect(): void;
-    /** Close the broker connection (resolves once closed). The devices stay registered; connect() again reuses them. */
-    disconnect(): Promise<void>;
-    registerDevice(name: string, endpointId: string, displayCategory: DisplayCategory | DisplayCategory[] | null): Device;
-    /** Forget a device (its listeners with it). Returns false when there was none. */
-    unregisterDevice(endpointId: string): boolean;
-    /** Forget every device. */
-    clearDevices(): void;
-    getDevices(): Device[];
-    getDevice(endpointId: string): Device | undefined;
-    getRootTopic(): string;
-    getHost(): string;
-}
-export default Alex2MQTT;