Attribute executor skill invocations to plugins (#39309)

## What changed

- Carry selected plugin identities from MCP discovery into per-turn extension data, limited to capability roots that are ready for the turn.
- Annotate executor skill catalog entries with the matching plugin ID and `user` scope.
- Include that attribution in `skill_invocation` analytics for both explicit and implicit executor skill invocations.

## Testing

- Extend the executor skills app-server test to verify plugin ID, skill scope, and invocation type for explicit and implicit analytics events.

GitOrigin-RevId: 9345600ae29bcb8eb894fffd2d6f7b05f22ebf74

codex-rs/core/src/session/mod.rs

@@ -3193,6 +3193,19 @@ impl Session {
         }
         .or_cancel(cancellation_token)
         .await?;
+        let mut selected_plugins = self
+            .services
+            .thread_extension_data
+            .get::<codex_extension_api::SelectedPluginSnapshot>()
+            .map(|snapshot| snapshot.as_ref().clone())
+            .unwrap_or_default();
+        selected_plugins.plugins.retain(|plugin| {
+            ready_selected_capability_roots
+                .iter()
+                .any(|root| root.id == plugin.selected_root_id)
+        });
+        extension_data.insert(selected_plugins.clone());
+        turn_context.extension_data.insert(selected_plugins);
         let tool_router = turn::built_tools(
             self.as_ref(),
             turn_context.as_ref(),