[KeyffMS]

Addresses #116.

Changes:

• publishes SettingsChangedEventArgs with an explicit transaction origin;
• gives each settings use-case context a private origin token;
• removes ConfigurationForm._committingGridValue;
• removes VisualProfileManagerForm._committingLocalChange;
• removes RuntimeCoordinator._committingSettings;
• local UI/runtime commands perform their intended post-commit follow-up exactly once and ignore only their own generic callback;
• external changes still refresh interested components;
• nested/reentrant commits retain independent origins;
• existing failure rollback and profile-manager refresh behavior remain covered;
• documents the synchronous event timing and origin contract.