Add level progress indicator to show learner progression across levels

Currently, the game does not provide a clear indication of how many levels a learner has completed or how many remain.
This issue proposes adding a simple level progress indicator displayed at the top-left corner of the screen in the format:

`Level Progress: 1 / 3`

The indicator updates automatically as the learner completes each level, helping users better understand their progression through the Event-Driven Architecture patterns without introducing gamified point-based scoring.
This improvement focuses on learning clarity and user orientation, especially for first-time learners navigating multiple EDA concepts.