fix(services): add in-memory caching to Codeforces and CodeChef services

[Rajen5145]

Description

Summary of Changes

Implements in-memory caching using githubCache in the Codeforces and CodeChef services to prevent hitting external API rate limits (e.g., Codeforces HTTP 429 errors) and reduce proxy load on rapid dashboard refreshes.

Motivation / Context

• Resolves Missing caching mechanism in Codeforces and CodeChef services leading to API rate-limiting #154
• Unlike GitHub and LeetCode services, Codeforces and CodeChef previously made live API requests on every invocation.
• Codeforces strictly enforces a rate limit of 1 request per 2 seconds, which caused HTTP 429 failures during concurrent or repeated profile views.
• CodeChef queries an external proxy (competeapi.vercel.app), which risked IP blocking and latency overhead without caching.

Key Modifications

• src/services/codeforces.service.js:
  • Added validation for missing handle.
  • Implemented cache check (codeforces:${handle}) prior to fetching data.
  • Stored successful responses in githubCache.
• src/services/codechef.service.js:
  • Added validation for missing handle.
  • Implemented cache check (codechef:${handle}) prior to fetching data.
  • Stored successful responses in githubCache.
• src/services/tests/codechef.service.test.js & src/services/tests/codeforces.service.test.js:
  • Added beforeEach hook calling githubCache.clear() to ensure isolated test execution across multiple mocked scenarios.

Verification & Testing

• Ran test suite locally via npm test.
• All 19 test suites and 322 individual tests passed.
• Verified that consecutive queries for the same handle return cached responses.

[vercel]

@Rajen5145 is attempting to deploy a commit to the Dot_NotSam's projects Team on Vercel.

A member of the Team first needs to authorize it.