- Add nil checks for session.TargetRef in all four execute*Action handlers
(Trader/Exchange/Model/Strategy) to prevent panic on corrupted sessions;
actions that don't need a target (query/query_list/create) are excluded.
- Fix toast.success indentation in handleToggleTrader so success messages
only fire when the API call actually succeeds.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>