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/mcp.rs

@@ -259,6 +259,7 @@ impl Session {
                 executor_capability_discovery.as_deref(),
             )
             .await;
+        let selected_plugins = mcp_projection.selected_plugins.clone();
         let input = self.build_mcp_runtime_input(
             &desired,
             mcp_projection,
@@ -269,7 +270,9 @@ impl Session {
             input.mcp_servers.contains_key(CODEX_APPS_MCP_SERVER_NAME),
             "unknown MCP server '{CODEX_APPS_MCP_SERVER_NAME}'"
         );
-        self.services.mcp_runtime.replace_fresh(input).await
+        let refreshed = self.services.mcp_runtime.replace_fresh(input).await;
+        self.services.thread_extension_data.insert(selected_plugins);
+        refreshed
     }
 
     pub(super) fn mark_mcp_runtime_dirty(&self) {