0f919237ea
- Add in_plan_mode flag to Agent struct - Add set_plan_mode() and is_plan_mode() methods - Gate check now only runs when in_plan_mode is true - CLI calls set_plan_mode(true) on /plan command and EnterPlanMode - CLI calls set_plan_mode(false) on approval and CTRL-D exit - Update integration test to enable plan mode - Fix test YAML to use Vec<Check> for negative/boundary checks