Use cache in event-message-handler.ts

[Mohit-Davar]

Description

The EventMessageHandler performs a database lookup for every incoming event to verify user admission status (isAdmitted) and balance.

Problem

• Increased latency in event processing
• High database load under heavy traffic
• Scalability bottlenecks on relays handling large event volumes

Expected Behavior

User admission status and balance checks should be efficient and should not require repeated database queries for every event.

Solution

Implement a Redis-based caching layer (as specified in the handler's TODO) to:

• Cache user admission status and balance
• Reduce redundant database queries
• Improve performance and scalability