feat: Migrate to GraphQL and Performance Optimization

[0xliam627]

Description

This PR migrates the EndGit API from REST to GraphQL to improve client performance and resolve over-fetching issues. We also integrated Apollo Server with Express and added Redis caching to heavily optimize the getHome query throughput.

Changelog

• Migrate to GraphQL and optimize performance
• Optimize backend queries
• Optimize getUserRepos to use concurrency, caching, and server-side filtering
• Run code quality fixes (format)

Fixes # (performance issues and GraphQL migration)

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings