rate limiter changed from module to class

[igorbenav]

Redis Rate Limiter Initialization Fix

Problem

The application was experiencing race conditions and state management issues with Redis initialization, particularly affecting the rate limiting functionality. When running with Uvicorn's auto-reload feature, module-level variables were being reset, causing the Redis client to be uninitialized even after startup.

Key issues:

• Redis client was sometimes reported as uninitialized even after startup completion
• Inconsistent state between module reloads during development
• Race conditions between FastAPI startup and Redis initialization

Solution

Refactored the rate limiter implementation to use a singleton pattern, providing more reliable state management and initialization:

1. Created a RateLimiter class to replace module-level variables:

   • Implements singleton pattern to maintain state
   • Provides clear initialization and client access methods
   • Better handles Redis connection lifecycle

2. Updated dependency injection:

   • Modified rate limiter dependency to use the new class

3. Enhanced initialization process:

   • Clear separation between initialization and usage
   • More reliable state management during development with auto-reload

closes #151