Configurable toolbars

[devmobasa]

Summary

• Add stable toolbar item/group IDs and config-driven hidden-item support.
• Apply hidden toolbar items to sizing, rendering, and hit testing.
• Preserve unknown/future toolbar item IDs across config saves.
• Add configurator controls for toolbar visibility, now in a dedicated Toolbar Visibility tab.
• Add overlay toolbar customization UI with grouped visibility controls.
• Add a default-hidden Screenshot top-toolbar item.
• Update docs and example config for toolbar item visibility.