Module learn_state 

Tab & Focus State Management for Learn Page

Manages the state for the integrated learn page experience:

• Tab modes (Lesson, Examples, Practice, Test)
• Focus state (which era/module is expanded)
• Exercise navigation within modes

Structs

FocusState

Tracks which era is currently focused (expanded)

ModuleTabState

State for a single module’s tab interface

Enums

TabMode

The four tab modes available for each module