Expose permission_mode in statusLine JSON input

Summary

The custom statusLine command receives a JSON object on stdin, but it does not include the current session-level permission mode (the one toggled via shift+tab).

The field permission_mode is already available in the hooks JSON schema (with values "default", "plan", "acceptEdits", "dontAsk", "bypassPermissions"), but it is absent from the statusline input.

Use case

I have a custom statusline that displays contextual info (model, git branch, session name, token usage). I'd like to also show the active permission mode — but .permissions.defaultMode only reflects the persistent setting from settings.json, not the session override set via shift+tab.

Request

Please expose permission_mode (the session-level active mode) in the JSON object piped to custom statusLine commands, matching the field already available in hooks.