As a user, I want to see which kanji are mastered in each category

Rationale:
The "Stats" section currently provides an overview of kanji mastery levels, ranging from "aka-chan" to "sensei." However, there is no way to see exactly which kanji fall within each mastery category. This lack of detail makes it difficult to track one's progress and focus on specific kanji one needs to improve.

Description:
I suggest implementing a new view that shows users the specific kanjis they’ve learned within each mastery category. This would provide more transparency in the learning process and help to focus on kanji that are not fully mastered yet.