346ae48b0c
- Restricted `setModel` to persist settings only when `persist: true` is passed; all runtime switches (Ctrl+P, `--model`, `/model`, model picker temp selections) no longer overwrite `modelRoles.default`.
- Changed `cycleRoleModels` to accept a direction ("forward"/"backward") instead of a `temporary` flag; both directions now use `applyRoleModel` without persisting.
- Added `persist: true` exclusively to the model picker's "Set as default" action in `SelectorController`.
- Added test suite covering persistence behavior for `setModel`, `cycleRoleModels`, and `cycleModel`.