Fix crawl stats retrieval by adding error handling and correct SQL syntax

Add requirements and settings for Scrapy web crawler

Add docker-compose configuration for PostgreSQL, RabbitMQ, Elasticsearch, and Redis services

Implement PolitenessEnforcer to manage crawl request delays per domain

Add RabbitMQ consumer and publisher implementations for crawl tasks

Update go.mod and go.sum to include new dependencies for xxhash, go-rendezvous, redis, and atomic

Add HashRing implementation for Redis-based load balancing

Fix error handling in IndexPage function for Elasticsearch indexing

Add Elasticsearch client initialization and document indexing functions

Add Bloom filter implementation with hashing functions

Add database initialization and frontier management functions

Initialize web crawler module with models and dependency management

Update go.mod and go.sum with additional dependencies; refactor InitRedis function to accept context and return error

Implement API for URL shortening and redirection

Add SystemDesign-go module dependency and update go.sum