application: channels bounded context

CQRS use cases (create/update/delete/get/list/list_by_owner),
ownership checks, auto-snapshot on config change.
Channel setters added to domain model.

crates/application/src/channels/get.rs

@@ -0,0 +1,16 @@
+use domain::models::Channel;
+use domain::value_objects::ChannelId;
+use domain::DomainResult;
+
+use super::deps::ChannelQueryDeps;
+use super::queries::GetChannelQuery;
+
+/// Get a single channel by ID.
+pub async fn execute(deps: &ChannelQueryDeps, query: GetChannelQuery) -> DomainResult<Option<Channel>> {
+    let channel_id = ChannelId::from(query.channel_id);
+    deps.channel_query.find_by_id(channel_id).await
+}
+
+#[cfg(test)]
+#[path = "tests/get.rs"]
+mod tests;