✨ Enhancement: Add Course Completion Percentage Indicator for Certificate Progress

[RitoG09]

The JSON Schema Tour currently provides chapter-based learning and interactive exercises, eventually awarding a certificate upon completion. However, users have no way to track how much of the course they have completed or how close they are to earning the certificate.

Adding a course completion percentage indicator (similar to platforms like Udemy, Coursera etc.) would significantly improve the learning experience by offering clear visibility into progress.

we can add something like this.

[RitoG09]

Hi @JeelRajodiya , Please let me know if this suggestion aligns with the project goals, if yes then I want to work on this.