The bridge subscribed to <root>/#, so the broker sent back every discover_r, alexaResponce and changeReport
the bridge published, and the backend's <endpointId>/alexaDirective_e. It now subscribes to <root>/discover
and <root>/+/alexaDirective, both named in src/topics.ts; a directive topic is recognised by the root and the
last segment instead of by counting three segments.
The test reads the subscriptions from the broker, publishes seven other topics under the root and one
directive for each of two endpoints: the bridge receives the two directives and the discovery request,
nothing else. Tests: 148 -> 150 (the count in the body of 6789a1a, 108 -> 113, should read 143 -> 148).
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
src/transport.ts has the Publisher interface, MqttPublisher (the client the bridge has at the time) and
MemoryPublisher (tests without a broker); src/topics.ts names the four topics the library publishes to.
Device, AlexaStatusMessage, AlexaErrorResponse and sendSceneResponse shared three copies of the
publish-and-report code: they now call one send() that resolves the topic or "" and never rejects.
registerDevice() and addDevice() work before connect(); a send() without a connection resolves "" and the
"error" event says to call connect(). unregisterDevice() and clearDevices() take the publisher from the device.
Device.setMqttClient() is gone, the first constructor argument of Device is ignored, and the message classes
take a Publisher where they took the client. Tests: 108 -> 113.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
