Introduce caching for read operations #72

To enhance performance and reduce latency, we are planning to implement caching for various operations, targeting both contest and user data. This strategic addition aims to achieve the following benefits:

Accelerate the prediction of ratings

• Alleviate the database load
• Enhance the speed of read operations on both web and extension platforms

Implementing caching will not only optimize the overall system responsiveness but also contribute to a smoother and more efficient user experience.