Make automatic refactoring opt-in and keep new member naming local

Automatic refactoring should be disabled by default and controlled by a global option in Settings. Editing a new member's name repeatedly while remaining in its metadata panel should complete member setup directly, even when automatic refactoring is enabled. Leaving the Name field to edit another metadata field must not cause a later name correction to open a global rename preview.

Explicit Rename Symbol commands remain available regardless of the setting.