refactor: derive Ruby action namespaces from Rust catalog

src/editor.rs

@@ -476,6 +476,15 @@ const CORE_ACTIONS: &[(&str, Action, &[Mode])] = &[
     ),
 ];
 
+/// Serializes the authoritative action names without copying the catalog.
+pub(crate) struct CoreActionCatalog;
+
+impl Serialize for CoreActionCatalog {
+    fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        serializer.collect_seq(CORE_ACTIONS.iter().map(|(name, _, _)| *name))
+    }
+}
+
 impl Action {
     fn named(mode: Mode, name: &str) -> Option<Self> {
         CORE_ACTIONS