Operator: custom action buttons for module actions

[andrewmarconi]

Parent

Part of #29

Summary

Expose module-defined actions (show, hide, reset, emphasize) as large, prominent buttons in the Operator UI with configurable labels and icons.

Scope

• Read available actions from module manifests
• Render action buttons in the ContextPanel or a dedicated action bar
• Support configurable labels and icons per action
• Fire actions via the existing /action API endpoint
• Visual feedback on action execution (loading state, confirmation)