feat(plugin): harden V4 host integration

Preserve legacy wire indices and route concurrent V4 responses and background requests by correlation and stable tab ID.

crates/ocs_plugin_api/src/host.rs

@@ -256,10 +256,6 @@ impl<'de> Deserialize<'de> for PluginNotification {
     }
 }
 
-/// An add-on package's entry point: its manifest, optional ribbon tab, and
-/// command dispatch. Built-in (in-tree) and dynamically-loaded (cdylib) plugins
-/// implement the same trait from this crate, so an out-of-tree add-on targets
-/// the stable contract rather than the host binary.
 /// An add-on package's entry point: its manifest, optional ribbon tab, and
 /// command dispatch. Built-in (in-tree) and dynamically-loaded (cdylib) plugins
 /// implement the same trait from this crate, so an out-of-tree add-on targets