Task: Discover notification channels dynamically

This page documents a task in the Comms substrate evolution story. It captures the goal, current status, acceptance, and any notes or results.

1. Goal

Replace client-side hardcoded channel lists with server-side dynamic discovery.

Server-side event_channel_registry service.
New protocol messages: list_event_channels_request (0x0015), list_event_channels_response (0x0016).
Shell events channels queries the registry; events listen * subscribes to every discovered channel.
Registry covers country_changed, change_reason_changed, change_reason_category_changed alongside existing channels.

Captured during execution; cleared into the parent story on close.

Removes the per-feature client edit when a new channel is added on the server.

Event channels are discoverable; clients self-update when the server adds channels.